feat(aio): report application errors to Google Analytics (#22011)

This is a basic implementation of error logging using the limited
facilities provided by Google Analytics.

Errors within the Angular app itself will be handled by a new
`ReportingErrorHandler` service, which overrides and extends the
built-in `ErrorHandler`.

Further, errors outside the app, which arrive at `window.onerror`
will also be reported to Google Analytics.

Closes #21943

PR Close #22011

aio/src/index.html

@@ -52,6 +52,38 @@
   </script>
   <!-- End Google Analytics -->
 
+  <script>
+    // Report fatal errors to Google Analytics
+    window.onerror = function() {
+      ga('send', 'exception', {exDescription: formatError.apply(null, arguments), exFatal: true});
+
+      function formatError(msg, url, line, col, e) {
+        var stack;
+        msg = msg.replace(/^Error: /, '');
+        if (e) {
+          stack = e.stack
+              // strip the leading "Error: " from the stack trace
+              .replace(/^Error: /, '')
+              // strip the message from the stack trace, if present
+              .replace(msg + '\n', '')
+              // strip leading spaces
+              .replace(/^ +/gm, '')
+              // strip all leading "at " for each frame
+              .replace(/^at /gm, '')
+              // replace long urls with just the last segment: `filename:line:column`
+              .replace(/(?: \(|@)http.+\/([^/)]+)\)?(?:\n|$)/gm, '@$1\n')
+              // replace "eval code" in Edge
+              .replace(/ *\(eval code(:\d+:\d+)\)(?:\n|$)/gm, '@???$1\n')
+        } else {
+          line = line || '?';
+          col = col || '?';
+          stack = url + ':' + line + ':' + col;
+        }
+        return (msg + '\n' + stack).substr(0, 150);
+      }
+    };
+  </script>
+
   <script>
     if (window.document.documentMode) {
       // polyfill IE11 in a blocking way