Remove assertion
Remove assertion

This assertion is too strong in some we have an under-constrained
expression for which the error has still not been emitted.

sjrd/dotty,lampepfl/dotty,lampepfl/dotty,lampepfl/dotty,som-snytt/dotty,lampepfl/dotty,lampepfl/dotty,dotty-staging/dotty,dotty-staging/dotty,som-snytt/dotty,sjrd/dotty,som-snytt/dotty,sjrd/dotty,sjrd/dotty,som-snytt/dotty,dotty-staging/dotty,sjrd/dotty,som-snytt/dotty,dotty-staging/dotty,dotty-staging/dotty