This is the same thing that annoys me most when writing Zig.
Unused variables / unused local constants being a hard error is just so ridiculously annoying.
Yes, I want to be able to know if there are unused variables and maybe have an option to make it an error.
Opt-in though.
I don't know how but somehow Go's unused variable error is more annoying than Rust's borrow checker. That's quite an achievement.