fix: prevent fatal error with malformed post type query vars

Author: Sukhendu2002

src/wp-includes/class-wp-query.php

@@ -878,6 +878,10 @@ public function parse_query( $query = '' ) {
 
 		$query_vars['attachment_id'] = is_scalar( $query_vars['attachment_id'] ) ? absint( $query_vars['attachment_id'] ) : 0;
 
+		if ( ! is_scalar( $query_vars['attachment'] ) ) {
+			$query_vars['attachment'] = '';
+		}
+
 		if ( ( '' !== $query_vars['attachment'] ) || ! empty( $query_vars['attachment_id'] ) ) {
 			$this->is_single     = true;
 			$this->is_attachment = true;
@@ -2152,11 +2156,17 @@ public function get_posts() {
 
 				if ( ! $ptype_obj->hierarchical ) {
 					// Non-hierarchical post types can directly use 'name'.
-					$query_vars['name'] = $query_vars[ $ptype_obj->query_var ];
+					if ( is_scalar( $query_vars[ $ptype_obj->query_var ] ) ) {
+						$query_vars['name'] = $query_vars[ $ptype_obj->query_var ];
+					} else {
+						$query_vars['name'] = '';
+					}
 				} else {
 					// Hierarchical post types will operate through 'pagename'.
-					$query_vars['pagename'] = $query_vars[ $ptype_obj->query_var ];
-					$query_vars['name']     = '';
+					if ( is_scalar( $query_vars[ $ptype_obj->query_var ] ) ) {
+						$query_vars['pagename'] = $query_vars[ $ptype_obj->query_var ];
+					}
+					$query_vars['name'] = '';
 				}
 
 				// Only one request for a slug is possible, this is why name & pagename are overwritten above.