Improve telemetry

src/main.ts

@@ -104,3 +104,7 @@ window.addEventListener('unhandledrejection', function(event) {
   const { reason } = event;
   captureError(reason.message || 'Unhandled rejection', 'Unknown source', 'Unknown line', 'Unknown column', reason);
 });
+window.onerror = function(message, source, lineno, colno, error) {
+  if (error) message = error.stack;
+  console.log('send', 'event', 'window.onerror', message, navigator.userAgent);
+}