Uh oh!
There was an error while loading. Please reload this page.
fix(core): Prevent functionToStringIntegration from throwing on cross-origin realms - #22273
Merged
mydea merged 3 commits intoJul 17, 2026
Merged
Conversation
Contributor
size-limit report 📦
|
There was a problem hiding this comment.
Cursor Bugbot has reviewed your changes and found 1 potential issue.
❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.
Reviewed by Cursor Bugbot for commit 69701ca. Configure here.
| let context = thisArg; | ||
| try { | ||
| if (SETUP_CLIENTS.has(getClient()!) && originalFunction) { |
There was a problem hiding this comment.
Unguarded non-null assertion
Low Severity
New non-null assertion on getClient()! has no comment explaining why a safer type is impossible. Elsewhere in this package the usual pattern is to bind getClient() and null-check before use, which also avoids the assertion. Flagged because it was mentioned in the PR review guidelines rules file.
Triggered by project rule: PR Review Guidelines for Cursor Bot
Reviewed by Cursor Bugbot for commit 69701ca. Configure here.
MemberAuthor
There was a problem hiding this comment.
this is fine, if we do has(undefined) it will simply return false
…-origin realms The patched `Function.prototype.toString` reads the Sentry carrier off `getClient()` on every invocation. When `this` (or the global object) is a `WindowProxy` whose browsing context was navigated cross-origin, that read throws a `SecurityError`. Since the patch lives on `Function.prototype`, any third-party `.toString()` call hits it, turning harmless introspection into uncatchable error noise. Wrap the patch body in a try/catch and fall back to the native `toString` so it never throws where the native impl would not. Fixes#21965 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
mydeaforce-pushed
the
francesconovy/js-2926-functiontostring-integrations-patched
branch
from
July 15, 2026 10:38
69701ca to
2f8b46eComparemydea
marked this pull request as ready for review
July 15, 2026 10:39
mydea
requested review from
a team, isaacs, nicohrubec and s1gr1d
and removed request for
a teamJuly 17, 2026 07:08
nicohrubec
approved these changes
Jul 17, 2026
Uh oh!
There was an error while loading. Please reload this page.
mydea
deleted the
francesconovy/js-2926-functiontostring-integrations-patched
branch
July 17, 2026 07:55
49 tasks
3 tasks
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The default
functionToStringIntegrationpatchesFunction.prototype.toString. The patched function reads the Sentry carrier offgetClient()(→getMainCarrier()→getSentryCarrier(GLOBAL_OBJ)→GLOBAL_OBJ.__SENTRY__) on every.toString()invocation.GLOBAL_OBJis aWindowProxyin browser realms. When its browsing context is later navigated cross-origin while code from the old realm can still be invoked (e.g. a parent window holding a reference into a same-origin child iframe whosesrcchanged to a cross-origin URL), the__SENTRY__read throws aSecurityError.Because the patch lives on
Function.prototype, the throw is triggered by any third-party.toString()call, converting harmless introspection into uncatchableSecurityErrornoise that Sentry then reports as unhandled-rejection events.Root cause
The native
Function.prototype.toStringnever throws for these calls — the throw is introduced solely by the integration's internal carrier access. The fix wraps the patch body in atry/catchand falls back tooriginalFunctionToString.apply(this, args), mirroring the defensive style already used around the patch installation. This keeps the unwrap behavior intact for live realms and degrades to exact native semantics when the carrier read throws.Fixes#21965
🤖 Generated with Claude Code