Issue #3327596: $request->get may no longer return array as of Symfony 6.0 (BadRequestException)

src/Plugin/facets/url_processor/QueryString.php

@@ -315,7 +315,7 @@ class QueryString extends UrlProcessorPluginBase {
     $url_parameters = $this->request->query;
 
     // Get the active facet parameters.
-    $active_params = $url_parameters->get($this->filterKey);
+    $active_params = $url_parameters->all()[$this->filterKey] ?? "";
     $facet_source_id = $this->configuration['facet']->getFacetSourceId();
 
     // When an invalid parameter is passed in the url, we can't do anything.