2.8.2: Gecode::FlatZinc::AST::TypeError

rotating-workforce-scheduling:

```
> minizinc rotating-workforce-scheduling.mzn rws-instance-e-25-s-7.dzn
terminate called after throwing an instance of 'Gecode::FlatZinc::AST::TypeError'
=====ERROR=====
```

opt-cryptanalysis:

```
> minizinc mznc2017_aes_opt.mzn r1.dzn 
terminate called after throwing an instance of 'Gecode::FlatZinc::AST::TypeError'
=====ERROR=====
```
