Fix crash in ReplicationController

Signed-off-by: Kamil Tekiela <[email protected]>

src/Controllers/Server/ReplicationController.php

@@ -75,7 +75,7 @@ public function __invoke(ServerRequest $request): Response
                 $request->getParsedBodyParamAsString('username', ''),
                 $request->getParsedBodyParamAsString('pma_pw', ''),
                 $request->getParsedBodyParamAsString('hostname', ''),
-                (int) $request->getParsedBodyParamAsString('text_port'),
+                (int) $request->getParsedBodyParamAsStringOrNull('text_port'),
             );
         }