Method check_stale

g2all/900/rop/900.js:271–276

()

    }

    check_stale() {
        if (this.is_stale) {
            throw Error('chain already ran, clean it first');
        }
        this.is_stale = true;
    }
    check_is_empty() {
        if (this.position === 0) {
            throw Error('chain is empty');