[clang] [Clang] Fixed getPredefinedExprDecl Assert When No Lambda Scope (PR #221713)

[Shengxin Pei via cfe-commits]

https://github.com/TPPPP72 commented:

In short, I do not agree with removing this assertion. We could replace it—for instance, by renaming `Before` to something more meaningful in your code and using that as the new invariant.
It is foreseeable that when `Before` is `true`, the current Clang implementation fails to maintain the correctness of the compiler's internal state.

https://github.com/llvm/llvm-project/pull/221713