Function validateTimeUnit

validateTimeUnit(timeUnit: string): undefined | string
Validates the provided time unit string and returns it if it is either 'MILLISECOND' or 'MICROSECOND'.
Parameters
- timeUnit: string
  The time unit string to be validated.
Returns undefined | string
The validated time unit string, or undefined if the input is falsy.

Throws
If the time unit is not 'MILLISECOND' or 'MICROSECOND'.
- Defined in common/src/utils.ts:188