Post-sort holes were caused by the planning phase, not the execution
phase. When GetContainerItemInfo/Link transiently returns nil for an
occupied slot during server lag, CreateBagFromID marks it <EMPTY>, the
sort algorithm moves real items into that "destination", and we end up
with literal gaps where the misclassified items used to be.
Validate the read against GetContainerNumFreeSlots before sorting; if
counts disagree, print a chat warning and abort instead of corrupting
the layout. User retries after a moment.
florian.berthold
da2d323018