fix(node): report errorMiddleware errors as unhandled (#8048)

Author: chdsbd

packages/node-integration-tests/suites/express/handle-error/test.ts

@@ -11,8 +11,8 @@ test('should capture and send Express controller error.', async () => {
       values: [
         {
           mechanism: {
-            type: 'generic',
-            handled: true,
+            type: 'middleware',
+            handled: false,
           },
           type: 'Error',
           value: 'test_error',

packages/node/src/handlers.ts

@@ -10,6 +10,7 @@ import {
 import type { Span } from '@sentry/types';
 import type { AddRequestDataToEventOptions } from '@sentry/utils';
 import {
+  addExceptionMechanism,
   addRequestDataToTransaction,
   baggageHeaderToDynamicSamplingContext,
   dropUndefinedKeys,
@@ -304,6 +305,11 @@ export function errorHandler(options?: {
           }
         }
 
+        _scope.addEventProcessor(event => {
+          addExceptionMechanism(event, { type: 'middleware', handled: false });
+          return event;
+        });
+
         const eventId = captureException(error);
         // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
         (res as any).sentry = eventId;