Merge pull request laravel#8700 from morganhein/5.0

[5.0] Fix for using closure with callable middleware

src/Illuminate/Routing/Route.php

@@ -620,7 +620,7 @@ protected function findCallable(array $action)
 	{
 		return array_first($action, function($key, $value)
 		{
-			return is_callable($value);
+			return is_callable($value) && is_numeric($index);
 		});
 	}