Add a cast to stop PHP spewing warnings

lib/punbb/include/dblayer/pgsql.php

@@ -122,7 +122,7 @@ class DBLayer
 
 			++$this->num_queries;
 
-			$this->last_query_text[$this->query_result] = $sql;
+			$this->last_query_text[(int)$this->query_result] = $sql;
 
 			return $this->query_result;
 		}