From 13d2c42039b485da7c0fbf7379ebbd02f3c26feb Mon Sep 17 00:00:00 2001
From: Yonas Habteab <yonas.habteab@netways.de>
Date: Wed, 3 Nov 2021 16:49:20 +0100
Subject: [PATCH] `UrlMigrator`: Discard invalid legacy url params when
 transforming

---
 library/Icingadb/Compat/UrlMigrator.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/library/Icingadb/Compat/UrlMigrator.php b/library/Icingadb/Compat/UrlMigrator.php
index 4b06ef86..603fc57b 100644
--- a/library/Icingadb/Compat/UrlMigrator.php
+++ b/library/Icingadb/Compat/UrlMigrator.php
@@ -64,7 +64,9 @@ class UrlMigrator
         if (! $url->getParams()->isEmpty()) {
             $filter = QueryString::parse((string) $url->getParams());
             $filter = self::transformFilter($filter, $queryTransformer);
-            $url->setQueryString(QueryString::render($filter));
+            if ($filter) {
+                $url->setQueryString(QueryString::render($filter));
+            }
         }
 
         return $url;