fix: Wrap event.target access in try/catch

Author: kamilogorek

packages/browser/src/helpers.ts

@@ -188,7 +188,15 @@ export function breadcrumbEventHandler(eventName: string, debounce: boolean = fa
     lastCapturedEvent = event;
 
     const captureBreadcrumb = () => {
-      const target = htmlTreeAsString(event.target as Node);
+      let target;
+
+      // Accessing event.target can throw (see getsentry/raven-js#838, #768)
+      try {
+        target = event.target ? htmlTreeAsString(event.target as Node) : htmlTreeAsString((event as unknown) as Node);
+      } catch (e) {
+        target = '<unknown>';
+      }
+
       if (target.length === 0) {
         return;
       }

packages/utils/src/misc.ts

@@ -1,4 +1,5 @@
 import { Event, Integration, WrappedFunction } from '@sentry/types';
+
 import { isString } from './is';
 
 /** Internal */
@@ -259,7 +260,7 @@ export function htmlTreeAsString(elem: Node): string {
   // try/catch both:
   // - accessing event.target (see getsentry/raven-js#838, #768)
   // - `htmlTreeAsString` because it's complex, and just accessing the DOM incorrectly
-  //   can throw an exception in some circumstances.
+  // - can throw an exception in some circumstances.
   try {
     let currentElem: Node | null = elem;
     const MAX_TRAVERSE_HEIGHT = 5;

packages/utils/src/object.ts

@@ -1,9 +1,9 @@
 import { ExtendedError, WrappedFunction } from '@sentry/types';
 
-import { isError, isPrimitive, isSyntheticEvent, isEvent, isElement } from './is';
+import { isElement, isError, isEvent, isPrimitive, isSyntheticEvent } from './is';
 import { Memo } from './memo';
-import { truncate } from './string';
 import { htmlTreeAsString } from './misc';
+import { truncate } from './string';
 
 /**
  * Wrap a given object method with a higher-order function
@@ -104,12 +104,23 @@ function getWalkSource(
     } = {};
 
     source.type = value.type;
-    source.target = isElement(value.target)
-      ? htmlTreeAsString(value.target)
-      : Object.prototype.toString.call(value.target);
-    source.currentTarget = isElement(value.currentTarget)
-      ? htmlTreeAsString(value.currentTarget)
-      : Object.prototype.toString.call(value.currentTarget);
+
+    // Accessing event.target can throw (see getsentry/raven-js#838, #768)
+    try {
+      source.target = isElement(value.target)
+        ? htmlTreeAsString(value.target)
+        : Object.prototype.toString.call(value.target);
+    } catch (_oO) {
+      source.target = '<unknown>';
+    }
+
+    try {
+      source.currentTarget = isElement(value.currentTarget)
+        ? htmlTreeAsString(value.currentTarget)
+        : Object.prototype.toString.call(value.currentTarget);
+    } catch (_oO) {
+      source.currentTarget = '<unknown>';
+    }
 
     // tslint:disable-next-line:strict-type-predicates
     if (typeof CustomEvent !== 'undefined' && value instanceof CustomEvent) {