Wrap all user-provided callbacks in try/catch and degrade gracefully #23755

Open
Open
Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
Assignees
msonnb

Description

@msonnb
msonnb
opened on Aug 31, 2026

Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).

Current state in the JS SDK

  • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
  • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
  • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.

Target behavior

Per the project's matrix:

CallbackOn throw / rejection
beforeSend, beforeSendTransactiondebug-log internal error, drop event
beforeSendLogdebug-log, drop log
beforeSendMetricdebug-log, drop metric
beforeSendSpandebug-log, emit original span (already done)
beforeBreadcrumbdebug-log, drop breadcrumb
tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
profilesSamplerdebug-log, fall back to profilesSampleRate
event processorsdebug-log, drop event
initialScope / integrations fn / other option callbacksdebug-log, fall back to default

Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.

Scope notes

  • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
  • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
  • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
  • Add tests for each callback: sync throw, async rejection, invalid return value.

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    , 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
     blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

    Skip to content
    Wrap all user-provided callbacks in try/catch and degrade gracefully #23755
    Open
    Open
    Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
    Assignees
    msonnb
    Description
    @msonnb
    msonnb
    opened on Aug 31, 2026
    Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).
    Current state in the JS SDK
    • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
    • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
    • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.
    Target behavior
    Per the project's matrix:
    CallbackOn throw / rejection
    beforeSend, beforeSendTransactiondebug-log internal error, drop event
    beforeSendLogdebug-log, drop log
    beforeSendMetricdebug-log, drop metric
    beforeSendSpandebug-log, emit original span (already done)
    beforeBreadcrumbdebug-log, drop breadcrumb
    tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
    profilesSamplerdebug-log, fall back to profilesSampleRate
    event processorsdebug-log, drop event
    initialScope / integrations fn / other option callbacksdebug-log, fall back to default
    Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.
    Scope notes
    • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
    • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
    • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
    • Add tests for each callback: sync throw, async rejection, invalid return value.
    Metadata
    Metadata
    Assignees
    Labels
    No labels
    No labels
    Projects
    No projects
      Milestone
      No milestone
      Relationships
      None yet
      Development
      No branches or pull requests
      Issue actions
      
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

      Skip to content
      Wrap all user-provided callbacks in try/catch and degrade gracefully #23755
      Open
      Open
      Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
      Assignees
      msonnb
      Description
      @msonnb
      msonnb
      opened on Aug 31, 2026
      Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).
      Current state in the JS SDK
      • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
      • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
      • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.
      Target behavior
      Per the project's matrix:
      CallbackOn throw / rejection
      beforeSend, beforeSendTransactiondebug-log internal error, drop event
      beforeSendLogdebug-log, drop log
      beforeSendMetricdebug-log, drop metric
      beforeSendSpandebug-log, emit original span (already done)
      beforeBreadcrumbdebug-log, drop breadcrumb
      tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
      profilesSamplerdebug-log, fall back to profilesSampleRate
      event processorsdebug-log, drop event
      initialScope / integrations fn / other option callbacksdebug-log, fall back to default
      Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.
      Scope notes
      • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
      • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
      • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
      • Add tests for each callback: sync throw, async rejection, invalid return value.
      Metadata
      Metadata
      Assignees
      Labels
      No labels
      No labels
      Projects
      No projects
        Milestone
        No milestone
        Relationships
        None yet
        Development
        No branches or pull requests
        Issue actions
        
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

        Skip to content
        Wrap all user-provided callbacks in try/catch and degrade gracefully #23755
        Open
        Open
        Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
        Assignees
        msonnb
        Description
        @msonnb
        msonnb
        opened on Aug 31, 2026
        Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).
        Current state in the JS SDK
        • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
        • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
        • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.
        Target behavior
        Per the project's matrix:
        CallbackOn throw / rejection
        beforeSend, beforeSendTransactiondebug-log internal error, drop event
        beforeSendLogdebug-log, drop log
        beforeSendMetricdebug-log, drop metric
        beforeSendSpandebug-log, emit original span (already done)
        beforeBreadcrumbdebug-log, drop breadcrumb
        tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
        profilesSamplerdebug-log, fall back to profilesSampleRate
        event processorsdebug-log, drop event
        initialScope / integrations fn / other option callbacksdebug-log, fall back to default
        Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.
        Scope notes
        • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
        • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
        • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
        • Add tests for each callback: sync throw, async rejection, invalid return value.
        Metadata
        Metadata
        Assignees
        Labels
        No labels
        No labels
        Projects
        No projects
          Milestone
          No milestone
          Relationships
          None yet
          Development
          No branches or pull requests
          Issue actions
          
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

          Skip to content
          Wrap all user-provided callbacks in try/catch and degrade gracefully #23755
          Open
          Open
          Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
          Assignees
          msonnb
          Description
          @msonnb
          msonnb
          opened on Aug 31, 2026
          Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).
          Current state in the JS SDK
          • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
          • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
          • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.
          Target behavior
          Per the project's matrix:
          CallbackOn throw / rejection
          beforeSend, beforeSendTransactiondebug-log internal error, drop event
          beforeSendLogdebug-log, drop log
          beforeSendMetricdebug-log, drop metric
          beforeSendSpandebug-log, emit original span (already done)
          beforeBreadcrumbdebug-log, drop breadcrumb
          tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
          profilesSamplerdebug-log, fall back to profilesSampleRate
          event processorsdebug-log, drop event
          initialScope / integrations fn / other option callbacksdebug-log, fall back to default
          Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.
          Scope notes
          • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
          • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
          • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
          • Add tests for each callback: sync throw, async rejection, invalid return value.
          Metadata
          Metadata
          Assignees
          Labels
          No labels
          No labels
          Projects
          No projects
            Milestone
            No milestone
            Relationships
            None yet
            Development
            No branches or pull requests
            Issue actions
            
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

            Skip to content
            Wrap all user-provided callbacks in try/catch and degrade gracefully #23755
            Open
            Open
            Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
            Assignees
            msonnb
            Description
            @msonnb
            msonnb
            opened on Aug 31, 2026
            Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).
            Current state in the JS SDK
            • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
            • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
            • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.
            Target behavior
            Per the project's matrix:
            CallbackOn throw / rejection
            beforeSend, beforeSendTransactiondebug-log internal error, drop event
            beforeSendLogdebug-log, drop log
            beforeSendMetricdebug-log, drop metric
            beforeSendSpandebug-log, emit original span (already done)
            beforeBreadcrumbdebug-log, drop breadcrumb
            tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
            profilesSamplerdebug-log, fall back to profilesSampleRate
            event processorsdebug-log, drop event
            initialScope / integrations fn / other option callbacksdebug-log, fall back to default
            Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.
            Scope notes
            • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
            • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
            • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
            • Add tests for each callback: sync throw, async rejection, invalid return value.
            Metadata
            Metadata
            Assignees
            Labels
            No labels
            No labels
            Projects
            No projects
              Milestone
              No milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

              Skip to content
              Wrap all user-provided callbacks in try/catch and degrade gracefully #23755
              Open
              Open
              Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
              Assignees
              msonnb
              Description
              @msonnb
              msonnb
              opened on Aug 31, 2026
              Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).
              Current state in the JS SDK
              • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
              • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
              • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.
              Target behavior
              Per the project's matrix:
              CallbackOn throw / rejection
              beforeSend, beforeSendTransactiondebug-log internal error, drop event
              beforeSendLogdebug-log, drop log
              beforeSendMetricdebug-log, drop metric
              beforeSendSpandebug-log, emit original span (already done)
              beforeBreadcrumbdebug-log, drop breadcrumb
              tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
              profilesSamplerdebug-log, fall back to profilesSampleRate
              event processorsdebug-log, drop event
              initialScope / integrations fn / other option callbacksdebug-log, fall back to default
              Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.
              Scope notes
              • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
              • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
              • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
              • Add tests for each callback: sync throw, async rejection, invalid return value.
              Metadata
              Metadata
              Assignees
              Labels
              No labels
              No labels
              Projects
              No projects
                Milestone
                No milestone
                Relationships
                None yet
                Development
                No branches or pull requests
                Issue actions
                
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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                Wrap all user-provided callbacks in try/catch and degrade gracefully #23755
                Open
                Open
                Wrap all user-provided callbacks in try/catch and degrade gracefully#23755
                Assignees
                msonnb
                Description
                @msonnb
                msonnb
                opened on Aug 31, 2026
                Part of Wrap all SDK user callbacks in a try catch (triggered by INC-2332, where a throwing traces_sampler in the Python SDK took down ingest).
                Current state in the JS SDK
                • beforeSendSpan is the only per-hook isolation (applyBeforeSendSpanCallback → log + keep original span).
                • beforeSend, beforeSendTransaction, beforeSendLog, beforeSendMetric, and event processors are covered only by the pipeline-level catch in Client._processEvent, which drops the event and captures the throw as a newhandled: false/mechanism: internalevent — burning quota and surfacing as a product issue. Logs/metrics don't go through that path at all.
                • tracesSampler (packages/core/src/tracing/sampling.ts), beforeBreadcrumb (packages/core/src/breadcrumbs.ts), profilesSampler, initialScope, integrations callback, ignoreSpans-style filters and friends are not isolated: a throw propagates into the host application.
                Target behavior
                Per the project's matrix:
                CallbackOn throw / rejection
                beforeSend, beforeSendTransactiondebug-log internal error, drop event
                beforeSendLogdebug-log, drop log
                beforeSendMetricdebug-log, drop metric
                beforeSendSpandebug-log, emit original span (already done)
                beforeBreadcrumbdebug-log, drop breadcrumb
                tracesSamplerdebug-log, fall back to parent decision, else tracesSampleRate
                profilesSamplerdebug-log, fall back to profilesSampleRate
                event processorsdebug-log, drop event
                initialScope / integrations fn / other option callbacksdebug-log, fall back to default
                Rules: never re-throw into the app, never capture the SDK's own failure as an event (see never capture your own exceptions). Async rejections must behave like sync throws. Record drops as client_report outcomes where a drop happens.
                Scope notes
                • Audit packages/core for every option that accepts a function and every client.on(...) hook path; add a shared helper rather than per-site try/catch.
                • Replace the captureException(..., mechanism: internal) in _processEvent with log + drop. This is a behavior change worth a changelog entry; decide whether it needs a major.
                • Consider unifying with @sentry/react-native's safeFactory / safeTracesSampler, which already implement part of this.
                • Add tests for each callback: sync throw, async rejection, invalid return value.
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