fix: return default value for FieldWithFileSize.maxFileSize

CHANGELOG.md

@@ -3,9 +3,9 @@
 ## [Unreleased]
 
 - fix: Check if classes are loaded by a different autoloader before attempting to autoload them. H/t @cvanh
+- fix: Return `wp_max_upload_size()` instead of `null` if `FieldWithFileSize.maxFileSize` is `null`. H/t @Gytjarek
 - ci: Replace calls to `docker-compose` with `docker compose`.
 
-
 ## v0.13.0
 
 **:warning: This release contains multiple breaking changes.**

src/Type/WPInterface/FieldSetting/FieldWithFileSize.php

@@ -36,6 +36,10 @@ public static function get_fields(): array {
 			'maxFileSize' => [
 				'type'        => 'Int',
 				'description' => __( 'The maximum size (in MB) an uploaded file may be .', 'wp-graphql-gravity-forms' ),
+				'resolve'     => static function ( $source ) {
+					// Fall back to the WP max upload size if the field setting is not set, to mimic GF frontend behavior.
+					return ! empty( $source->maxFileSize ) ? (int) $source->maxFileSize : ( wp_max_upload_size() / 1048576 );
+				},
 			],
 		];
 	}