Looks to be related to context registers being removed after the
context register holder itself was already removed.

Structure initialization can't work with this: if it was initialized as
an int then used later as a struct, none of the struct's fields are
there, so writting to them is not doable.

There might be a way, using `remove` and `initialize` to refresh the
register at every use. This would kill the side-channel attack used to
pass parameters, and so special care would have to be taken for them.

The 'SetValue' Wyrd instruction is no longer allowed to write to a
non-existing memory element.

And a few blackjack things.

I think so are seen frequently enough to warrant an addition.