message: fix(browser): Set severity level for events captured by the global error handler
  Set severity level in events captured by the global `onerror`, for use in event processing (`beforeSend` or a global event processor).
diff: @@ -101,6 +101,8 @@ function _installGlobalOnErrorHandler(): void {
  column,
  );
  + event.level = Severity.Error;
  +
  addMechanismAndCapture(hub, error, event, 'onerror');
  },
  );
  