Fixed bug when no filters have been provided to count endpoint (#1165)

Author: jessevz

src/inc/apiv2/common/AbstractModelAPI.class.php

@@ -623,6 +623,7 @@ public function count(Request $request, Response $response, array $args): Respon
     $expands = $this->makeExpandables($request, $validExpandables);
 
     $objects = [$factory->getNullObject()];
+    $aFs = [];
     //build join filters
     foreach ($expands as $expand) {
       $relation = $this->getToManyRelationships()[$expand];