Fix #16188 by zipping less
(This is a second attempt at !207 (closed), after rebasing.)
There was an awful lot of zipping going on in canDecomposableTyConAppOK, and one of the lists being zipped was too short, causing the result to be too short. Easily fixed.
Also fixes #16204 (closed) and #16225 (closed)
test cases: typecheck/should_compile/T16188
typecheck/should_compile/T16204[ab]
typecheck/should_fail/T16204c
typecheck/should_compile/T16225