Add assertion on invalid cache set

[weswigham]

This is the assertion originally from #43835, in a separate PR for post-RC cut, per this comment

[TrySpace]

Is it possible to have a more informative message? I've been stuck with this generic: [object Object] === [object Object] error:

 `Error: Debug Failure. Expected [object Object] === [object Object]. Parameter symbol already has a cached type which differs from newly assigned type

And I'm unable to update typescript since 4.1.5, and it's impossible to manually trial and error by disabling pieces of code with a large codebase.