Parser parses an if statement followed by a tuple as a function call instead of a sequence

[iAmMichaelConnor]

Aim

I've tried to distill it to a minimal example, but it was a complicated bit of aztec3 code i was writing.
I've tested this not very minimal example (but as minimal as I could cause the error) with v0.4.1. It's a horrible example. The code was doing lots of stuff, and I just started stripping things out whilst trying to retain the error.

NOTICE: when we remove the constrain liine, it causes this error. If we reinstate the constrain line, the error disappears. Not sure why I need a constrain here.

fn main(a: Field, condition: bool) -> pub bool {

    let (b, arr) = foo(a, condition);
    arr[0] == 4 + b
}

fn foo(a: Field, condition: bool) -> (Field, [Field; 2]) {

    let mut arr: [Field; 2] = [1, 2];

    if condition {
        arr[0] = a;
    } else {
        arr[0] = 4;
    }
    // NOTICE: no idea why I need this constraint here... or what the error means when you remove it.
    // constrain arr[0] == 4;

    (a, arr)
}

error: Expected a function, but found a(n) ()
   ┌─ /mnt/user-data/mike/packages/yarn-project/noir-contracts/src/contracts/mike-play/src/main.nr:11:5
   │  
11 │ ╭     if condition {
12 │ │         arr[0] = a;
13 │ │     } else {
14 │ │         arr[0] = 4;
15 │ │     }
16 │ │     // TODO: no idea why I need this constraint here... or what the error means when you remove it.
17 │ │     // constrain arr[0] == 4;
18 │ │ 
19 │ │     (a, arr)
   │ ╰────────────'

error: aborting due to 1 previous errors
Error: Failed to compile circuit

Location:
    crates/nargo_cli/src/cli/mod.rs:71:5
    ```


### Expected behavior

.

### Bug

.

### To reproduce

1.
2.
3.
4.


### Installation method

None

### Nargo version

_No response_

### @noir-lang/noir_wasm version

_No response_

### @noir-lang/barretenberg version

_No response_

### @noir-lang/aztec_backend version

_No response_

### Additional context

_No response_

### Submission Checklist

- [ ] Once I hit submit, I will assign this issue to the Project Board with the appropriate tags.

[jfecher]

This is an interesting one. It is parsing the whole expression as a function call:

if condition {
    arr[0] = a;
} else {
    arr[0] = 4;
}(a, arr)

Hence why the constrain statement with its semicolon afterwards fixes it. I may have to look at the rust grammar a bit for this one since this is technically an ambiguous parse, but the right solution should be to restructure the parser a bit to favor them as two separate statements.