[refactor]: using expect instead of unwrap_or_else

[lxl66566]

currently the code uses a lot of .unwrap_or_else(|| { unreachable!("...") }); / .unwrap_or_else(|| { panic!("...") });. I think it's better to use exepct because it's more intuitive, and using less code.

Things to do:

1. allow expect in clippy global rule
2. replace code

[github-actions]

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[bsbds]

We could also consider replacing

let Some(x) = y else {
    unreachable!("...");
};

with

let x  = y.expect("...");

[LucienY01]

/assignme