nightly-2024-10-11: feat: slightly improve "unexpected token" error message (#6279)

# Description

## Problem

Tokens appear like `]` or `)` in error messages where showing them as
`']'` or `')'` might be clearer.

## Summary



## Additional Context



## Documentation

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.