enable fetch debugging

app/scripts/background.js

@@ -2,6 +2,9 @@
  * @file The entry point for the web extension singleton process.
  */
 
+// this needs to run before anything else
+require('./lib/setupFetchDebugging')()
+
 const urlUtil = require('url')
 const endOfStream = require('end-of-stream')
 const pump = require('pump')

app/scripts/lib/setupFetchDebugging.js

@@ -0,0 +1,34 @@
+module.exports = setupFetchDebugging
+
+//
+// This is a utility to help resolve cases where `window.fetch` throws a
+// `TypeError: Failed to Fetch` without any stack or context for the request 
+// https://github.com/getsentry/sentry-javascript/pull/1293
+//
+
+function setupFetchDebugging() {
+  if (!global.fetch) return
+  const originalFetch = global.fetch
+
+  global.fetch = wrappedFetch
+
+  async function wrappedFetch(...args) {
+    const initialStack = getCurrentStack()
+    try {
+      return await originalFetch.call(window, ...args)
+    } catch (err) {
+      console.warn('FetchDebugger - fetch encountered an Error', err)
+      console.warn('FetchDebugger - overriding stack to point of original call')
+      err.stack = initialStack
+      throw err
+    }
+  }
+}
+
+function getCurrentStack() {
+  try {
+    throw new Error('Fake error for generating stack trace')
+  } catch (err) {
+    return err.stack
+  }
+}