500 server error when posting data containing non-existent fields

I have a custom post type that I want to create via the REST API.

When I do a POST to /wp-json/wp/v2/tmd_event with the following data:

json
{
    "post_title": "Testing non-existing meta_box value",
    "post_status": "draft",
    "post_type": "tmd_event",
    "meta_box": {
        "test": "value" ## note: this is not a custom field that exists!
    }
}

I get the following error:

json
{
    "code": "internal_server_error",
    "message": "<p>There has been a critical error on this website.</p><p><a href=\"https://wordpress.org/documentation/article/faq-troubleshooting/\">Learn more about troubleshooting WordPress.</a></p>",
    "data": {
        "status": 500
    },
    "additional_errors": []
}

If I leave out the field, the post gets created as a draft.

I have looked into the WordPress debug.log, and found

[06-Aug-2023 17:47:23 UTC] PHP Fatal error:  Uncaught TypeError: RWMB_Field::process_value(): Argument #3 ($field) must be of type array, bool given, called in /var/www/html/wp-content/plugins/meta-box-aio/vendor/meta-box/mb-rest-api/class-mb-rest-api.php on line 219 and defined in /var/www/html/wp-content/plugins/meta-box/inc/field.php:206
Stack trace:
#0 /var/www/html/wp-content/plugins/meta-box-aio/vendor/meta-box/mb-rest-api/class-mb-rest-api.php(219): RWMB_Field::process_value('valuze', 48164, false)
#1 /var/www/html/wp-content/plugins/meta-box-aio/vendor/meta-box/mb-rest-api/class-mb-rest-api.php(84): MB_Rest_API->update_value(false, 'valuze', 48164)
#2 /var/www/html/wp-includes/rest-api/endpoints/class-wp-rest-controller.php(498): MB_Rest_API->update_post_meta(Array, Object(WP_Post), 'meta_box', Object(WP_REST_Request), 'tmd_event')
#3 /var/www/html/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php(747): WP_REST_Controller->update_additional_fields_for_object(Object(WP_Post), Object(WP_REST_Request))
#4 /var/www/html/wp-includes/rest-api/class-wp-rest-server.php(1181): WP_REST_Posts_Controller->create_item(Object(WP_REST_Request))
#5 /var/www/html/wp-includes/rest-api/class-wp-rest-server.php(1028): WP_REST_Server->respond_to_request(Object(WP_REST_Request), '/wp/v2/tmd_even...', Array, NULL)
#6 /var/www/html/wp-includes/rest-api/class-wp-rest-server.php(442): WP_REST_Server->dispatch(Object(WP_REST_Request))
#7 /var/www/html/wp-includes/rest-api.php(410): WP_REST_Server->serve_request('/wp/v2/tmd_even...')
#8 /var/www/html/wp-includes/class-wp-hook.php(308): rest_api_loaded(Object(WP))
#9 /var/www/html/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters('', Array)
#10 /var/www/html/wp-includes/plugin.php(565): WP_Hook->do_action(Array)
#11 /var/www/html/wp-includes/class-wp.php(399): do_action_ref_array('parse_request', Array)
#12 /var/www/html/wp-includes/class-wp.php(780): WP->parse_request('')
#13 /var/www/html/wp-includes/functions.php(1334): WP->main('')
#14 /var/www/html/wp-blog-header.php(16): wp()
#15 /var/www/html/index.php(17): require('/var/www/html/w...')
#16 {main}
  thrown in /var/www/html/wp-content/plugins/meta-box/inc/field.php on line 206