Typechecker stack overflow

There are some tests for the typechecker that are commented out because they're causing a stack overflow during executions. These tests are here: https://github.com/yatima-inc/yatima/tree/main/Tests/Typechecker

One that might be particularly interesting to debug is this one: https://github.com/yatima-inc/yatima/blob/main/Tests/Typechecker/Reject.lean#L9, since the fixture doesn't involve mutuals.

Start with the commented-out tests in Tests/Typechecker, especially Tests/Typechecker/Reject.lean at line 9, and run the typechecker test suite to reproduce the stack overflow. Trace the failure for the non-mutual fixture, then confirm that the affected tests can be enabled and execute without overflowing the stack.

Written by the indexing model from the issue text.