# Description
Refactors the code in `nu-cli`, `main.rs`, `run.rs`, and few others.
Namely, I added `EngineState::generate_nu_constant` function to
eliminate some duplicate code. Otherwise, I changed a bunch of areas to
return errors instead of calling `std::process::exit`.
# User-Facing Changes
Should be none.
# Description
Fixes#12813 where a panic occurs when syntax highlighting `not`. Also
fixes#12814 where syntax highlighting for `not` no longer works.
# User-Facing Changes
Bug fix.
