LevelBasedGraph is used a lot (Esp. in world level stuff) and appers to have edgecases where it breaks

However those edge cases mostly seem to be related to vilage code so it may be that that need poking instead and the general case can be parallelised (which would be good)

Notes:

• Currently processUpdates and scheduleUpdate are synchronised to fix the issue
• The synchronisation region could be reduced to just cover a small section of the executed code, potentially allowing multiple things to loop just not fetch at once