Port switchExprErrUnion optimization for both catch and if patterns,
fix missing rvalue call in decl table lookup, fix identAsString
ordering for underscore error captures, and fill value_placeholder
with 0xaa to match upstream undefined pattern.
Enables corpus build.zig test.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Add error capture scope to orelseCatchExpr (catch |err| now creates
a ScopeLocalVal for the captured error variable)
- Add @panic, @errorName, @field builtins
- Increase blockExprStmts scope arrays from 64 to 128 entries
(build.zig has 93 var decls in a single block)
corpus build.zig still skipped: needs switchExprErrUnion optimization
(catch |err| switch(err) pattern).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
