std: fix compile errors caught by stage2 AstGen

 * `comptime const` is redundant
 * don't use `extern enum`; specify a tag type.
   `extern enum` is only when you need tags to alias. But aliasing tags
   is a smell. I will be making a proposal shortly to remove `extern enum`
   from the language.
 * there is no such thing as `packed enum`.
 * instead of `catch |_|`, omit the capture entirely.
 * unused function definition with missing parameter name
 * using `try` outside of a function or test

0 files changed, 0 insertions, 0 deletions