```ts
/** The temperature in degrees Fahrenheit or Kelvin. */
export function celsiusToFahrenheitOrKelvin(celsius: number): number {
  if (typeof celsius !== "number" || !Number.isFinite(celsius)) {
    throw new Error("celsius must be a finite number");
  }
  const absoluteZero = -273.15;
  if (celsius < absoluteZero) {
    throw new Error("celsius must be at or above absolute zero");
  }
  return celsius * 1.8 + 32;
}

/** The temperature in kelvin. */
export function celsiusToKelvin(celsius: number): number {
  if (typeof celsius !== "number" || !Number.isFinite(celsius)) {
    throw new Error("celsius must be a finite number");
  }
  const absoluteZero = -273.15;
  if (celsius < absoluteZero) {
    throw new Error("celsius must be at or above absolute zero");
  }
  return celsius + 273.15;
}
```