Constructed types with dubious elements in the structure cause segfault

[Joachim Jansen]

Very early in the run of IDP (I assume somewhere during parsing and structure creation) a segfault is thrown for the following example:

vocabulary V {
    type t constructed from { C(string), C(int) }
}

theory T : V {}

structure S : V {
    t = {C("3"); C(2)}
}

[Bart Bogaerts]

Duplicate of #933.