As per the comment in TypeEnv.normalize_tv about cancellation, whenever we create a TypeVar we must assert that there is no under/overflow. To make sure this always happen move the safety checks to TypeVar.derived() from the other helper methods
As per the comment in TypeEnv.normalize_tv about cancellation, whenever we create a TypeVar we must assert that there is no under/overflow. To make sure this always happen move the safety checks to TypeVar.derived() from the other helper methods