Type-check filter results at call-sites to avoid type errors.

Author: dmsnell

src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php

@@ -442,6 +442,7 @@ static function ( $format ) {
 		 * @param WP_REST_Request $request The REST API request.
 		 */
 		$args       = apply_filters( "rest_{$this->post_type}_query", $args, $request );
+		$args       = is_array( $args ) ? $args : array();
 		$query_args = $this->prepare_items_query( $args, $request );
 
 		$posts_query  = new WP_Query();

src/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php

@@ -299,6 +299,7 @@ public function get_items( $request ) {
 
 			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php */
 			$args       = apply_filters( 'rest_revision_query', $args, $request );
+			$args       = is_array( $args ) ? $args : array();
 			$query_args = $this->prepare_items_query( $args, $request );
 
 			$revisions_query = new WP_Query();