Bug #5925 / Delete subrecord element: row remain visible

delete.php: it seems that assign an array element to a string variable does not convert the string to an array. CR thought this was the case in the past (maybe a change in PHP7.2)

extension/qfq/api/delete.php

@@ -79,13 +79,14 @@ try {
     $answer = $qfq->delete();
 
     // in case everything is fine, an empty string is returned. Else an Array.
-    $flagSuccess = ($answer == '');
+    $flagSuccess = ($answer === '');
 
     $targetUrl = Store::getVar(SIP_TARGET_URL, STORE_SIP);
     $modeAnswer = Store::getVar(SIP_MODE_ANSWER, STORE_SIP);
 
     switch ($modeAnswer) {
         case MODE_JSON:
+            $answer = array();
             if ($flagSuccess) {
                 $answer[API_MESSAGE] = 'Deleted';
                 $answer[API_REDIRECT] = API_ANSWER_REDIRECT_CLIENT;