Satisfy clippy

[Urhengulas]

Fix multiple clippy warnings:

• useless conversion to the same type: u128
• useless use of format!
• called .as_ref().map(|s| &**s) on an Option value. This can be done more directly by calling mod_path.as_deref() instead
• you seem to be trying to use match for destructuring a single pattern. Consider using if let

Surpress:

• returning an Err(_) with the ? operator

[jonas-schievink]

Looks good! But we can fix the last warning too

[jonas-schievink]

bors r+

[bors]

Build succeeded:

• ci