fix(proxy): surface upstream error cause and distinguish timeouts (#757)

Author: harlan-zw

packages/script/src/runtime/server/proxy-handler.ts

@@ -355,7 +355,11 @@ export default defineEventHandler(async (event) => {
 log('[proxy] Fetching:',targetUrl)
 
 constcontroller=newAbortController()
-consttimeoutId=setTimeout(()=>controller.abort(),15000)// 15s timeout
+lettimedOut=false
+consttimeoutId=setTimeout(()=>{
+timedOut=true
+controller.abort()
+},15000)// 15s timeout
 
 // Resolve the fetch body: passthrough streams the raw request, otherwise serialize
 letfetchBody: BodyInit|undefined
@@ -381,9 +385,14 @@ export default defineEventHandler(async (event) => {
 catch(err){
 log('[proxy] Upstream error:',err)
 throwcreateError({
-statusCode: 502,
-statusMessage: 'Bad Gateway',
+statusCode: timedOut ? 504 : 502,
+statusMessage: timedOut ? 'Gateway Timeout' : 'Bad Gateway',
 message: `Proxy upstream request failed: ${targetUrl}`,
+cause: err,
+data: {
+errorName: (errasError)?.name,
+errorCode: timedOut ? 'TIMEOUT' : (erras{code?: string})?.code,
+},
 })
 }
 finally{