Crashes for `var opt 0..infinity`

[simonihmig]

MiniZinc crashes when I declare a variable with both opt and an upper bound of infinity (same for lower bound).

This crashes:

var opt 0..infinity: dummy;

but all of the following variable declarations do work as expected:

var opt 0..100: dummy; % dummy = <>
var opt int: dummy; % dummy = <>
var 0..infinity: dummy; % dummy = 0