DSLX: A for loop with non-const upper bound

Hello!
If in the DSL file in the for loop, if I specify not a constant but a variable in the upper bound of the range, then the interpreter get the message:

```rust
#![test]
fn test_for()
{
let a = u8:3;
// const a = u8:3;
let _ = for (i, acc) : (u8, u8) in range (u8:0, a)
{
acc + i
}(u8:0);
()
}
```

```bash
$ /interpreter_main /test_for.x

E0422 08:51:22.003500 6664 command_line_utils.cc:35] Could not extract a textual position from error message: NOT_FOUND: Could not find bindings entry for identifier: "a" @ /test_for.x:6:53-6:54: INVALID_ARGUMENT: Provided status is not in recognized error form: NOT_FOUND: Could not find bindings entry for identifier: "a" @ /test_for.x:6:53-6:54
F0422 08:51:22.003547 6664 interpreter_main.cc:147] Check failed: ::absl::OkStatus() == (status) (OK vs. NOT_FOUND: Could not find bindings entry for identifier: "a" @ /test_for.x:6:53-6:54)
```

If you specify a constant, it goes fine.
Please, is there any workaround to use the variable?