[BUGFIX] Check if facet value is set

Author: spoonerWeb

Classes/Domain/Search/ResultSet/Facets/UrlFacetContainer.php

@@ -159,7 +159,7 @@ public function getActiveFacetValuesByName(string $facetName): array
         }
         array_map(static function ($activeFacet) use (&$values, $facetName) {
             $parts = explode(':', $activeFacet, 2);
-            if ($parts[0] === $facetName) {
+            if ($parts[0] === $facetName && isset($parts[1])) {
                 $values[] = $parts[1];
             }
         }, $activeFacets);