Variant segfault

[Inkrementator]

Adresses part of #10518, now adding to Variant(Variant[string]) doesn't segfault anymore, but at least throws.

The issue was calling the destructor of unitinialized memory.

How to fix the exception is harder. I think there are 3 places where this could handled, either in get(T), tryPutting inside the handler, or case OpID.indexAssign: . Of these, tryPutting probably is the most "correct", but also seems the hardest to understand to me and will have the biggest fallout in unrelated places if you get it wrong.

Whatever place is eventually chosen, you can't just memcopy the storage, as big types are often implicitly allocated on the heap and stored as a pointer.

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[thewilsonator]

@Inkrementator does this build on #10690 ? Fixes for segfaults should go to stable, but if this requires code that is already in master to work then that is fine to target master.

[Inkrementator]

Sorry, I "ignored" this because I had issues building the stable branch on my machine.