How to use the @js-joda/core.IllegalStateException function in @js-joda/core

// Offset the ISO DOW by the start of this week
        const sow = this._weekDef.firstDayOfWeek().value();
        const dow = this._localizedDayOfWeek(temporal, sow);

        if (this._rangeUnit === ChronoUnit.WEEKS) {
            return dow;
        } else if (this._rangeUnit === ChronoUnit.MONTHS) {
            return this._localizedWeekOfMonth(temporal, dow);
        } else if (this._rangeUnit === ChronoUnit.YEARS) {
            return this._localizedWeekOfYear(temporal, dow);
        } else if (this._rangeUnit === IsoFields.WEEK_BASED_YEARS) {
            return this._localizedWOWBY(temporal);
        } else if (this._rangeUnit === ChronoUnit.FOREVER) {
            return this._localizedWBY(temporal);
        } else {
            throw new IllegalStateException('unreachable');
        }
    }

rangeRefinedBy(temporal) {
        if (this._rangeUnit === ChronoUnit.WEEKS) {
            return this._range;
        }

        let field = null;
        if (this._rangeUnit === ChronoUnit.MONTHS) {
            field = ChronoField.DAY_OF_MONTH;
        } else if (this._rangeUnit === ChronoUnit.YEARS) {
            field = ChronoField.DAY_OF_YEAR;
        } else if (this._rangeUnit === IsoFields.WEEK_BASED_YEARS) {
            return this._rangeWOWBY(temporal);
        } else if (this._rangeUnit === ChronoUnit.FOREVER) {
            return temporal.range(ChronoField.YEAR);
        } else {
            throw new IllegalStateException('unreachable');
        }

        // Offset the ISO DOW by the start of this week
        const sow = this._weekDef.firstDayOfWeek().value();
        const isoDow = temporal.get(ChronoField.DAY_OF_WEEK);
        const dow = MathUtil.floorMod(isoDow - sow, 7) + 1;

        const offset = this._startOfWeekOffset(temporal.get(field), dow);
        const fieldRange = temporal.range(field);
        return ValueRange.of(ComputedDayOfField._computeWeek(offset, fieldRange.minimum()),
            ComputedDayOfField._computeWeek(offset, fieldRange.maximum()));
    }

const woy = this._range.checkValidIntValue(value, this);
                const weeks = woy - this._localizedWeekOfYear(date, dateDow);
                days = weeks * 7 + (dow - dateDow);
            }
            date = date.plus(days, ChronoUnit.DAYS);
            if (resolverStyle === ResolverStyle.STRICT) {
                if (date.getLong(ChronoField.YEAR) !== fieldValues.get(ChronoField.YEAR)) {
                    throw new DateTimeException('Strict mode rejected date parsed to a different year');
                }
            }
            fieldValues.remove(this);
            fieldValues.remove(ChronoField.YEAR);
            fieldValues.remove(ChronoField.DAY_OF_WEEK);
            return date;
        } else {
            throw new IllegalStateException('unreachable');
        }
    }