Fix #16565, add missing RuntimeReps for unboxed tuples
Unboxed tuples and sums take extra RuntimeRep arguments, which must be manually passed in a few places. Three of them were missed.
This error was hidden because zipping functions in TyCoRep
ignored lists with mismatching length. This is now fixed; the lengths are now checked by calling zipEqual.
As suggested in #16565 (closed), I moved checking for isTyVar
and isCoVar
to zipTyEnv
and zipCoEnv
.