[sakoht]

Presuming if you are 100% sure what "invalid" is: It is possible that being _unable_ to represent a logic error might mean that a logic error is represented as a "valid but incorrect" value, which is even more dangerous.

Take the example of storing a continuous series of date ranges. If I only store the first date of each pair, I can never accidentally have an overlap or gap. But if my code has a logic error that incorrectly calculates a range, being able to represent it could throw an error. If that code error translates to an incorrect break-point instead, I haven't prevented a bug, I've hidden it.