Fix exception which is thrown on search results page

Author: wojtekn

app/code/Magento/Search/Model/SynonymAnalyzer.php

@@ -137,6 +137,7 @@ private function getSearchPattern(array $words): string
         $patterns = [];
         for ($lastItem = count($words); $lastItem > 0; $lastItem--) {
             $phrase = implode("\s+", \array_slice($words, 0, $lastItem));
+            $phrase = preg_quote($phrase, '/');
             $patterns[] = '^' . $phrase . ',';
             $patterns[] = ',' . $phrase . ',';
             $patterns[] = ',' . $phrase . '$';