laravel 中间件return 'a';就报错，返回return redirect('/'); 就不报错是怎么回事？

Question

以下是错误提示

<!--
SymfonyComponentDebugExceptionFatalThrowableError: Argument 1 passed to IlluminateSessionMiddlewareStartSession::addCookieToResponse() must be an instance of SymfonyComponentHttpFoundationResponse, string given, called in D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateSessionMiddlewareStartSession.php on line 71 in file D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateSessionMiddlewareStartSession.php on line 169
Stack trace:

1. SymfonyComponentDebugExceptionFatalThrowableError->() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateSessionMiddlewareStartSession.php:169
2. IlluminateSessionMiddlewareStartSession->addCookieToResponse() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateSessionMiddlewareStartSession.php:71
3. IlluminateSessionMiddlewareStartSession->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151
4. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
5. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateCookieMiddlewareAddQueuedCookiesToResponse.php:37
6. IlluminateCookieMiddlewareAddQueuedCookiesToResponse->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151
7. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
8. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateCookieMiddlewareEncryptCookies.php:66
9. IlluminateCookieMiddlewareEncryptCookies->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151

1. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
2. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:104
3. IlluminatePipelinePipeline->then() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingRouter.php:684
4. IlluminateRoutingRouter->runRouteWithinStack() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingRouter.php:659
5. IlluminateRoutingRouter->runRoute() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingRouter.php:625
6. IlluminateRoutingRouter->dispatchToRoute() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingRouter.php:614
7. IlluminateRoutingRouter->dispatch() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateFoundationHttpKernel.php:176
8. IlluminateFoundationHttpKernel->IlluminateFoundationHttp{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:30
9. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorfideloperproxysrcTrustProxies.php:57
10. FideloperProxyTrustProxies->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151
11. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
12. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateFoundationHttpMiddlewareTransformsRequest.php:31
13. IlluminateFoundationHttpMiddlewareTransformsRequest->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151
14. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
15. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateFoundationHttpMiddlewareTransformsRequest.php:31
16. IlluminateFoundationHttpMiddlewareTransformsRequest->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151
17. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
18. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateFoundationHttpMiddlewareValidatePostSize.php:27
19. IlluminateFoundationHttpMiddlewareValidatePostSize->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151
20. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
21. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateFoundationHttpMiddlewareCheckForMaintenanceMode.php:62
22. IlluminateFoundationHttpMiddlewareCheckForMaintenanceMode->handle() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:151
23. IlluminatePipelinePipeline->IlluminatePipeline{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateRoutingPipeline.php:53
24. IlluminateRoutingPipeline->IlluminateRouting{closure}() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminatePipelinePipeline.php:104
25. IlluminatePipelinePipeline->then() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateFoundationHttpKernel.php:151
26. IlluminateFoundationHttpKernel->sendRequestThroughRouter() D:phpStudyPHPTutorialWWWqimilivendorlaravelframeworksrcIlluminateFoundationHttpKernel.php:116
27. IlluminateFoundationHttpKernel->handle() D:phpStudyPHPTutorialWWWqimilipublicindex.php:55

-->

以下是中间件出错的代码
public function handle($request, Closure $next)

{
    $userInfo = session('userInfo');
    if(empty($userInfo)){
        return redirect('/');
    }
    Log::info($userInfo->api_token);
    $api_token = $request->header('apiToken');
    Log::info($api_token);
    if($userInfo->api_token !== $api_token){
        return 'a';
    }
    return $next($request);

}

Answer 1

是要返回Response对象吧，用return respose('a');应该可以