"i + ret i" hits assertion "Cannot create binary operator with two operands of differing type!"

```
fn f(i: int) -> int { i + ret i; }
fn main() {
    f(2);
}
```

Assertion failed: (S1->getType() == S2->getType() && "Cannot create binary operator with two operands of differing type!"), function Create, file Instructions.cpp, line 1580.
