Remove assertion to fix error handling code
Remove assertion to fix error handling code

nathanielbaxter/libminizinc,tias/libminizinc,nathanielbaxter/libminizinc,jjdekker/libminizinc,jjdekker/libminizinc,jjdekker/libminizinc,nathanielbaxter/libminizinc,jjdekker/libminizinc,nathanielbaxter/libminizinc,tias/libminizinc