Exit program on presolving error
Exit program on presolving error

With the FlatZinc approach the model is no longer solvable. Solving
would still be possible with the original predicate, but the original
predicate calls would have to be reconstructed and flattened. This
doesn't seem worth it for now.

jjdekker/libminizinc,jjdekker/libminizinc,jjdekker/libminizinc,jjdekker/libminizinc