private _error(additional?: string) {
const lexeme = this._input.substring(this._start, this._current);
const errToken: Token = { type: TokenType.Error, offset: this._start, lexeme };
this._errors.push({ offset, lexeme, additionalInfo: additional });
this._tokens.push(errToken);
}
// u - unicode, y - sticky // TODO@ulugbekna: we accept double quotes as part of the string rather than as a delimiter (to preserve old parser's behavior)