Unused math expression doesn't warn or error

[asterite]

Aim

This code:

fn main() -> pub Field {
    let x = 1;
    if x != 0 {
        -1 * x
    }
    1
}

Expected Behavior

Should give a warning or an error, because -1 * x has no effect at all. An equivalent code in Rust gives an error saying "mismatched types" because one branch returns an integer, the other ().

Bug

Noir should check if branches have the same type, even if the if is a statement and not an expression.

To Reproduce

Workaround

None

Workaround Description

No response

Additional Context

No response

Project Impact

None

Blocker Context

No response

Nargo Version

No response

NoirJS Version

No response

Proving Backend Tooling & Version

No response

Would you like to submit a PR for this Issue?

None

Support Needs

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[asterite]

Interestingly, this is also valid Noir code:

fn main() {
    let x = if true { 1 };
}

The type of x ends up being () while Rust rejects it.

I guess "fixing" all of these might introduce some breaking changes.