load() {
		const doCheckACL = (!(this instanceof CBIJSONMap) && this.readonly == null);
		const loadTasks = [ doCheckACL ? callSessionAccess('uci', this.config, 'write') : true ];
		const configs = this.parsechain ?? [ this.config ];

		loadTasks.push(...configs.map(L.bind((config, i) => {
			return i ? L.resolveDefault(this.data.load(config)) : this.data.load(config);
		}, this)));

		return Promise.all(loadTasks).then(L.bind((res) =>  {
			if (res[0] === false)
				this.readonly = true;

			return this.loadChildren();
		}, this));
	}
Load the configuration covered by this map.

The `load()` function first loads all referenced UCI configurations,
then it recursively walks the form element tree and invokes the
load function of each child element.

@returns {Promise<void>}
Returns a promise resolving once the entire form completed loading all
data. The promise may reject with an error if any configuration failed
to load or if any of the child elements' load functions rejected with
an error.