resolveDefault(value, defvalue) {
			return Promise.resolve(value).catch(() => defvalue);
		}
Returns a promise resolving with either the given value or with
the given default in case the input value is a rejecting promise.

@instance
@memberof LuCI

@param {*} value
The value to resolve the promise with.

@param {*} defvalue
The default value to resolve the promise with in case the given
input value is a rejecting promise.

@returns {Promise<*>}
Returns a new promise resolving either to the given input value or
to the given default value on error.