Minizinc 2.8.1 compatibility issues

Dear,

I'm using Choco v 4.10.14 through the MiniZinc interface on MiniZinc v.2.8.1 and I am encountering an error when trying to compile a model with an element constraint.

Below is a minimal working example:
```
include "globals.mzn";

var bool: x;
var 1..5: idx;
array[1..5] of var bool: arr;

constraint element(idx, arr, x);
% constraint x == arr[idx]; % same result
```
**Output:**
```
[flatzinc_builtins:436.78-107](err:/snap/minizinc/896/share/minizinc/std/flatzinc_builtins.mzn?line=436&column=78):
MiniZinc: type error: Type array[int,int] of var float is not allowed in as a FlatZinc builtin argument, arrays must be one dimensional
[flatzinc_builtins:442.76-110](err:/snap/minizinc/896/share/minizinc/std/flatzinc_builtins.mzn?line=442&column=76):
MiniZinc: type error: Type array[int,int] of var set of int is not allowed in as a FlatZinc builtin argument, arrays must be one dimensional
Process finished with non-zero exit code 1.
```

The problem remains when trying to change the type of the array or x-variable to `int`.

Kind regards,
Ignace