Refactor actual code for remove items in queue.
- Rename RemoveBatch function in RemoveItem to be more general.
- Remove the For-loop for find the index to a findIndex.
Code style cleanup (var -> let, etc.).
Also clear cached entities when only its first element has removed in ProductionQueue:
- In the current state, RemoveBatch function cleans the entityCache and destroy the entities kept in memory whatever the element of the queue we want to delete.
- This entityCache stores the entities freshly created by SpawnUnits function ( that is used when we finish the production of the first batch in the queue).
- But when we may not be able to spawn all entities then these entities stays in the cache (to avoid being recreated) and reused until successful.
So I managed this to be executed only when we want delete the first element of the queue.