Merge pull request #4540 from Laravel-Backpack/add-is-string-check-for-invokable-class

[BUG] add more checks, change execution order in strippedRequest

Author: tabacitu

src/app/Library/CrudPanel/Traits/Fields.php

@@ -479,19 +479,19 @@ public function getStrippedSaveRequest($request)
     {
         $setting = $this->getOperationSetting('strippedRequest');
 
+        // if a closure was passed
+        if (is_callable($setting)) {
+            return $setting($request);
+        }
+
         // if an invokable class was passed
         // eg. \App\Http\Requests\BackpackStrippedRequest
-        if (class_exists($setting)) {
+        if (is_string($setting) && class_exists($setting)) {
             $setting = new $setting();
 
             return is_callable($setting) ? $setting($request) : abort(500, get_class($setting).' is not invokable.');
         }
 
-        // if a closure was passed
-        if (is_callable($setting)) {
-            return $setting($request);
-        }
-
         return $request->only($this->getAllFieldNames());
     }