Revert "fix reducing arity or chaperoning keyword-valued `prop:procedure`"

This reverts commit 5bae9773aaa2d68c71240b8d7b0b58f43fb21342.
Re-added error checks in the color=? function, so error message comes
from the function you actually called, rather than an internal.
(cherry picked from commit ca98f85c39bc439feb4d5239ee407c6df35f05a8)
Corrected expected error message to match actual error message.  Now
passes "raco test".
(cherry picked from commit 97ee349046e295d95fcd45e99d5dee5828ac9109)