```ts
export function durHours(minutes: number): number {
    if (minutes < 0) throw new Error("Invalid value for minutes");
    return Math.floor(minutes / 60);
}

export function durText(minutes: number): string {
    const hours = durHours(minutes);
    const remainingMinutes = minutes % 60;
    return `${hours}h${remainingMinutes < 10 ? '0' : ''}${remainingMinutes}m`;
}
```