fix php 8.1 deprecation issues caused by preg_replace error

Author: karyna-t

library/Zend/Db/Statement.php

@@ -198,6 +198,12 @@ protected function _stripQuoted($sql)
             $sql = preg_replace("/$q([^$q{$escapeChar}]*|($qe)*)*$q/s", '', $sql);
         }
 
+        if ($sql === null) {
+            // this preg_replace may return NULL in case of error (PREG_BACKTRACK_LIMIT_ERROR).
+            // In that case the result of this method will be an empty string.
+            return '';
+        }
+
         // get a version of the SQL statement with all quoted
         // values and delimited identifiers stripped out
         // remove "foo\"bar"