setPosition(lineIdx, column) {
        // We must not jump into a token!
        if (lineIdx === this.lineIdx) {
            this.lineCharOffset = column;
            if (this.line !== null) {
                this.lineTokenOffset = this.lineCharOffset === 0 ? 0 : this.lineTokens.findTokenIndexAtOffset(this.lineCharOffset);
            }
        }
        else {
            this.lineIdx = lineIdx;
            this.lineCharOffset = column;
            this.line = null;
        }
        this.peekedToken = null;
    }
Must be a zero line token. The end of the document cannot be peeked.