For private `define-values` in classes with multiple variables, don't
eagerly throw type errors in the synthesis step. Instead, wait
until the later checking step when the environment will be correctly
set up.
When the initial synthesis typecheck fails, yield type Any for
the environment. If the typecheck should really fail, this is ok. If
not, then the user can add a type annotation.
A better long-term strategy is to change the handling of environments
so that the type environment gets refined as definitions are checked.
This way all annotations that the user writes are factored into the
initial environment and unannotated variables will have their types
synthesized.
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