Cannot delete items already saved on map

Expected behavior:
- loading a saved tile map should still process saved placed items correctly
- the map load flow should complete even when saved item data is present
- OnMapLoaded and adjacency updates should still run after the load finishes

--- Original GitHub issue (auto-fetched) ---
Title: Cannot delete items already saved on map

Body:
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## Summary

Currently cannot delete items that are already saved on the tilemap. Items that are spawned by the user can be deleted though.

## Steps to Reproduce

Try to delete an item that starts on the map.

## Context

https://github.com/RE-SS3D/SS3D/assets/41941008/9403883b-07de-4949-a114-fe752203d502

Likely broken in recent PR and not noticed:
#1274 #1269
