DMN16 — Returning null is not enough for reporting/handling errors

Abusing null as an error indicator is not enough for reporting/handling errors.
In particular, it does not solve the need for users to:

• know exactly what the root cause of an error was
• control the reaction to errors

The specification already mentions error reporting but is neither a strict requirement nor consequently used:

When a built-in function encounters input that is outside its defined domain, the function SHOULD report or log diagnostic information if appropriate and SHALL return null.