Fix issue where union typed parameters caused discovery errors

[27pchrisl]

One of my controllers had a function that could be passed a union type, this caused an error during discovery:

   Error 

  Call to undefined method ReflectionUnionType::getName()

  at vendor/spatie/laravel-route-discovery/src/PendingRoutes/PendingRouteAction.php:54
     50▕     {
     51▕         /** @var ReflectionParameter $modelParameter */
     52▕         $modelParameter = collect($this->method->getParameters())->first(function (ReflectionParameter $parameter) {
     53▕             /** @phpstan-ignore-next-line */
  ➜  54▕             return is_a($parameter->getType()?->getName(), Model::class, true);
     55▕         });
     56▕ 
     57▕         $uri = '';
     58▕ 

This PR fixes the issue by ensuring the type is a ReflectionNamedType before attempting to call getName() on it.

[freekmurze]

Thank you!