[AST] Do not verify when allowing compiler errors

[bnbarham]

It isn't unexpected to have an invalid AST when allowing errors, so make
sure not to verify the AST in that case.

[bnbarham]

@akyrtzi there's a hidden frontend option -disable-ast-verifier that we could use rather than adding an extra condition to that function. Thoughts?

[akyrtzi]

@akyrtzi there's a hidden frontend option -disable-ast-verifier that we could use rather than adding an extra condition to that function. Thoughts?

This gets into compiler implementation details, I don't think a build system should need to be aware of such a flag.
And it's implementation detail about what a verifier is doing, e.g. we could have an AST verifier that checks things that apply when allowing errors as well instead of disabling it completely.

To double check, the AST verifier only runs when assertions are enabled, right?

[bnbarham]

To double check, the AST verifier only runs when assertions are enabled, right?

Or specifically enabled, yeah.

[bnbarham]

@swift-ci please test

[bnbarham]

Turns out that this is actually due to the skip function bodies flag. I'll look into it more, will convert this to draft for now so we don't accidentally merge.

[bnbarham]

Fixed this differently in #37701 - it was due to differing behaviour with a missing right brace in delayed vs non-delayed parsing.