sendCommand(method, params) {
		if (this.hasSession()) {
			return new Promise((res, rej) => {
				/** @type {Session} */
				(this.session).post(method, params, (err, params) => {
					if (err !== null) {
						rej(err);
					} else {
						res(params);
					}
				});
			});
		}
		return Promise.resolve();
	}
@param {string} method method name
@param {EXPECTED_OBJECT=} params params
@returns {Promise<EXPECTED_ANY | void>} Promise for the result