Reordered the $class variable

Author: rennokki

src/FlushQueryCacheObserver.php

@@ -71,12 +71,12 @@ public function restored(Model $model)
      */
     protected function invalidateCache(Model $model): void
     {
+        $class = get_class($model);
+
         if (! $model->getCacheTagsToInvalidateOnUpdate()) {
             throw new Exception('Automatic invalidation for '.$class.' works only if at least one tag to be invalidated is specified.');
         }
 
-        $class = get_class($model);
-
         $class::flushQueryCache(
             $model->getCacheTagsToInvalidateOnUpdate()
         );