Inheritance: extends SlackSlashCommandException
 public function __construct(Request $request)
 {
     parent::__construct($request);
     if (empty($this->signature)) {
         throw InvalidHandler::signatureIsRequired(static::class);
     }
     $this->signatureIsBound = $this->bindSignature($this->signature);
 }
 /**
  * @return \Spatie\SlashCommand\Handlers\BaseHandler
  *
  * @throws \Spatie\SlashCommand\Exceptions\RequestCouldNotBeHandled
  */
 protected function determineHandler()
 {
     $handler = collect($this->config->get('handlers'))->map(function (string $handlerClassName) {
         if (!class_exists($handlerClassName)) {
             throw InvalidHandler::handlerDoesNotExist($handlerClassName);
         }
         return new $handlerClassName($this->request);
     })->filter(function (HandlesSlashCommand $handler) {
         return $handler->canHandle($this->request);
     })->first();
     if (!$handler) {
         throw RequestCouldNotBeHandled::noHandlerFound($this->request);
     }
     return $handler;
 }