Incorrect upcasting of signed integers for comparsion

[nventuro]

Aim

After quite a bit of head-scratching I noticed certain signed integers seem to be incorrectly upcast when performing comparisons.

Bug

I expected the following test to pass, but it doesn't:

#[test]
fn test() {
    let a = 5;
    let b = -1;

    assert(a > b);
}

The test does pass as expected if I do a as i32.

[jfecher]

Looks like a and b are defaulting to u64s since > was used (otherwise they'd default to Fields). The -1 then presumably overflowed the u64's range.

[TomAFrench]

#4631 is relevant here as this would have been caught and fixed by Nico if we errored on this case rather than wrapping around.

[asterite]

Fixed by #5375

Now the above program gives this error:

[one] Running 1 test function
[one] Testing test... error: The value `-1` cannot fit into `u32` which has range `0..=4294967295`
  ┌─ src/main.nr:4:13
  │
4 │     let b = -1;
  │             --