Misleading error message when keyword used as identifier

[danielchasehooper]

Zig Version

0.14.0-dev.2198+e5f5229fd

Steps to Reproduce and Observed Behavior

The compiler produces poor error messages in these situations:

echo 'const align = 16;' > temp.zig && zig run temp.zig
temp.zig:1:7: error: expected 'an identifier', found 'align'
const align = 16;
      ^~~~~

echo 'pub fn resume() u8 { return 1; }' > temp.zig && zig run temp.zig
temp.zig:1:8: error: expected '(', found 'resume'
pub fn resume() u8 { return 1; }
       ^~~~~~

$ echo 'pub fn main() !void { return error.test; }' > temp.zig && zig run temp.zig
temp.zig:1:32: error: expected 'an identifier', found 'test'
pub fn main() !void { return error.test; }
                                   ^~~~

Expected Behavior

I originally encountered this by trying to return error.test from a function - I thought the error message was trying to tell me that all error values had to have an uppercase first letter, since the documentation for errors uses uppercase names, and switching to error.Test fixed the error. But it's actually because test is a keyword!

It would be helpful if the compiler told you that the identifier you're trying to use is a keyword and you need to either rename it or use the @"" syntax.

I'd be happy to make this change if someone from the core team gave me the go ahead.