--- class-wp-rest-posts-controller.php	2017-10-20 16:06:18.138226000 +0530
+++ class-wp-rest-posts-controller-new.php	2017-10-20 16:09:18.242232559 +0530
@@ -46,8 +46,10 @@
 		$this->post_type = $post_type;
 		$this->namespace = 'wp/v2';
 		$obj = get_post_type_object( $post_type );
-		$this->rest_base = ! empty( $obj->rest_base ) ? $obj->rest_base : $obj->name;
-
+		if ($obj) {
+			$this->rest_base = !empty($obj->rest_base) ? $obj->rest_base : $obj->name;
+		}
+		
 		$this->meta = new WP_REST_Post_Meta_Fields( $this->post_type );
 	}