From bd0649c317e95fc881a73fb3b772c8ba6e0abe3c Mon Sep 17 00:00:00 2001
From: Katie Byers <katie.byers@sentry.io>
Date: Fri, 14 Feb 2020 11:46:31 +0100
Subject: [PATCH] fix(integrations): Treat specific `CustomEvents` as promise
 rejections (#2429)

---
 CHANGELOG.md                                     |  2 ++
 .../browser/src/integrations/globalhandlers.ts   | 16 +++++++++++++++-
 packages/browser/src/loader.js                   |  4 ++--
 packages/integrations/src/dedupe.ts              |  6 +++---
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7f9e48beb9dd..3a6ba4bad3a9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- [browser] fix: Handle PromiseRejectionEvent-like CustomEvents
+
 ## 5.12.3
 
 - [apm] fix: Remove undefined keys from trace.context
diff --git a/packages/browser/src/integrations/globalhandlers.ts b/packages/browser/src/integrations/globalhandlers.ts
index 30c1e079a9e8..769ace766496 100644
--- a/packages/browser/src/integrations/globalhandlers.ts
+++ b/packages/browser/src/integrations/globalhandlers.ts
@@ -138,8 +138,22 @@ export class GlobalHandlers implements Integration {
 
     this._global.onunhandledrejection = function(e: any): boolean {
       let error = e;
+
+      // dig the object of the rejection out of known event types
       try {
-        error = e && 'reason' in e ? e.reason : e;
+        // PromiseRejectionEvents store the object of the rejection under 'reason'
+        // see https://developer.mozilla.org/en-US/docs/Web/API/PromiseRejectionEvent
+        if ('reason' in e) {
+          error = e.reason;
+        }
+        // something, somewhere, (likely a browser extension) effectively casts PromiseRejectionEvents
+        // to CustomEvents, moving the `promise` and `reason` attributes of the PRE into
+        // the CustomEvent's `detail` attribute, since they're not part of CustomEvent's spec
+        // see https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent and
+        // https://github.com/getsentry/sentry-javascript/issues/2380
+        else if ('detail' in e && 'reason' in e.detail) {
+          error = e.detail.reason;
+        }
       } catch (_oO) {
         // no-empty
       }
diff --git a/packages/browser/src/loader.js b/packages/browser/src/loader.js
index 17edc9c76075..16742a26e20c 100644
--- a/packages/browser/src/loader.js
+++ b/packages/browser/src/loader.js
@@ -200,9 +200,9 @@
 
   // Do the same store/queue/call operations for `onunhandledrejection` event
   var _oldOnunhandledrejection = _window[_onunhandledrejection];
-  _window[_onunhandledrejection] = function(exception) {
+  _window[_onunhandledrejection] = function(e) {
     queue({
-      p: exception.reason
+      p: 'reason' in e ? e.reason : 'detail' in e && 'reason' in e.detail ? e.detail.reason : e
     });
     if (_oldOnunhandledrejection) _oldOnunhandledrejection.apply(_window, arguments);
   };
diff --git a/packages/integrations/src/dedupe.ts b/packages/integrations/src/dedupe.ts
index effa8396bd11..ed8cea670cb5 100644
--- a/packages/integrations/src/dedupe.ts
+++ b/packages/integrations/src/dedupe.ts
@@ -61,7 +61,7 @@ export class Dedupe implements Integration {
     const currentMessage = currentEvent.message;
     const previousMessage = previousEvent.message;
 
-    // If no event has a message, they were both exceptions, so bail out
+    // If neither event has a message property, they were both exceptions, so bail out
     if (!currentMessage && !previousMessage) {
       return false;
     }
@@ -108,7 +108,7 @@ export class Dedupe implements Integration {
     let currentFrames = this._getFramesFromEvent(currentEvent);
     let previousFrames = this._getFramesFromEvent(previousEvent);
 
-    // If no event has a fingerprint, they are assumed to be the same
+    // If neither event has a stacktrace, they are assumed to be the same
     if (!currentFrames && !previousFrames) {
       return true;
     }
@@ -178,7 +178,7 @@ export class Dedupe implements Integration {
     let currentFingerprint = currentEvent.fingerprint;
     let previousFingerprint = previousEvent.fingerprint;
 
-    // If no event has a fingerprint, they are assumed to be the same
+    // If neither event has a fingerprint, they are assumed to be the same
     if (!currentFingerprint && !previousFingerprint) {
       return true;
     }