Slim4 - Route callbacks must return Response

1

Hey.
I’ve got TypeError from route callbacks on Slim4.
On Slim3, return value of route callbacks is either Psr\Http\Message\ResponseInterface or void(so no need to return).
On Slim4, if I don’t write return value of route callbacks as below,

$app->get("/hello", function(ServerRequestInterface $request, ResponseInterface $response, $args) {
    print("Hello world!");
});

and TypeError has occurred.

Hello world!
**Fatal error** : Uncaught TypeError: Return value of Slim\Handlers\Strategies\RequestResponse::__invoke() must implement interface Psr\Http\Message\ResponseInterface, null returned in /Users/Shinzo/htdocs/socymslim.localhost/firstslim/vendor/slim/slim/Slim/Handlers/Strategies/RequestResponse.php:42 Stack trace: 
#0 /Users/Shinzo/htdocs/socymslim.localhost/firstslim/vendor/slim/slim/Slim/Routing/Route.php(370): Slim\Handlers\Strategies\RequestResponse->__invoke(Object(Closure), Object(Slim\Psr7\Request), Object(Slim\Psr7\Response), Array) 
#1 /Users/Shinzo/htdocs/socymslim.localhost/firstslim/vendor/slim/slim/Slim/MiddlewareDispatcher.php(64): Slim\Routing\Route->handle(Object(Slim\Psr7\Request)) 
#2 /Users/Shinzo/htdocs/socymslim.localhost/firstslim/vendor/slim/slim/Slim/MiddlewareDispatcher.php(64): Slim\MiddlewareDispatcher->handle(Object(Slim\Psr7\Request)) 
#3 /Users/Shinzo/htdocs/socymslim.localhost/firstslim/vendor/slim/slim/Slim/Routing/Route.php(338): Slim\MiddlewareDispatcher->handle(Object(Slim\Psr7\Request)) 
#4 /Users/ in  **/Users/Shinzo/htdocs/socymslim.localhost/firstslim/vendor/slim/slim/Slim/Handlers/Strategies/RequestResponse.php**  on line  **42**

If I write return $response;, no error.
So, Slim4’s route callbacks must return Response always. Is this right?

2

This is not new from Slim 4. Route callbacks must return a Response object.

3

@l0gicgate Thank you for your reply! I understand.