Return early if an empty search is attempted

See: https://github.com/bolt/bolt/commit/bd823dee5919645b8c33ba4accc487e25735fa98#diff-62941ecfac9b632f60e6d0e5a8eac524

src/Storage/Query/Handler/SearchQueryHandler.php

@@ -34,6 +34,11 @@ class SearchQueryHandler
             $query->setContentType($contentType);
 
             $searchParam = $contentQuery->getParameter('filter');
+            /** If we have an empty search filter then we need to return early */
+            if (empty($searchParam)) {
+                return $set;
+            }
+
             $query->setParameters($contentQuery->getParameters());
             $query->setSearch($searchParam);