`InstanceContainer#copy()` does not work for unloaded instances

[zax71]

If you use an InstanceContainer that has not yet been loaded when copying it, the resultant InstanceContainer will be empty. To get around this, I can use InstanceContainer#loadChunk() but imo InstanceContainer#copy() should do this automatically

[mworzala]

This is expected behavior. You need to load the chunks you want to copy.

Loading them automatically does not make much sense. In most cases there is not a simple way to know all of the chunks, and loading them all is unnecessary at best, problematic at worst if it's a big world.