There are steps I followed:
1. I used the command "composer create-project flarum/flarum . --stability=beta" to install forum.
2. I try to start a new discussion then I got an error - "Oops! Something went wrong. Please reload the page and try again."
Now reload the home page then getting
Warning: count(): Parameter must be an array or an object that implements Countable in C:\xampp\htdocs\flarum\vendor\flarum\core\src\Core\Post\RegisteredTypesScope.php on line 52
Fatal error: Uncaught RuntimeException: Output has been emitted previously; cannot emit response in C:\xampp\htdocs\flarum\vendor\zendframework\zend-diactoros\src\Response\SapiEmitterTrait.php:31 Stack trace: #0 C:\xampp\htdocs\flarum\vendor\zendframework\zend-diactoros\src\Response\SapiEmitter.php(27): Zend\Diactoros\Response\SapiEmitter->assertNoPreviousOutput() #1 C:\xampp\htdocs\flarum\vendor\zendframework\zend-diactoros\src\Server.php(162): Zend\Diactoros\Response\SapiEmitter->emit(Object(Zend\Diactoros\Response)) #2 C:\xampp\htdocs\flarum\vendor\flarum\core\src\Http\AbstractServer.php(36): Zend\Diactoros\Server->listen(Object(Zend\Stratigility\NoopFinalHandler)) #3 C:\xampp\htdocs\flarum\index.php(16): Flarum\Http\AbstractServer->listen() #4 {main} thrown in C:\xampp\htdocs\flarum\vendor\zendframework\zend-diactoros\src\Response\SapiEmitterTrait.php on line 31
