Deleting a Tunnel construction site leaves energy on wall

[keenathar]

Which shard is affected?
All shards

What happened?
I had placed construction sites for Tunnels in a room, but changed my mind because of the high energy cost.
When I deleted a construction site that was already in progress, energy dropped on the construction site location - which, given that this was a tunnel, was on the terrain wall:

https://screeps.com/a/#!/history/shard2/W41N24?t=10647462 At the linked tick one build action has just been completed. The next tick the constructionSite is removed and the energy on top of the wall at (10, 20), though barely visible because the pile is only 11 energy big.

What should have happened?
I'm not really sure if the current behavior is intended behavior.
Personally I would expect the invested energy to drop on the nearest non-wall tile, or not drop at all.

How can we reproduce this?

1. Place a tunnel/road constructionSite on top of a terrain wall.
2. Wait for some building progress to have been made.
3. Destroy the constructionSite.

[artch]

Why is this an issue? You can still pick it up from an adjacent tile.

[keenathar]

@artch because it can also happen on tiles that are not adjacent to any walkable tile.

If the construction sites were removed in a different order, the site on (11, 20) would have been the one that had the progress and therefore energy drop on an inaccessible location.

[artch]

Yes, the same would happen when a tunnel disappears when some creep is staying there, it may find itself in a blocked location, and its tombstone will also be inaccessible. It feels consistent and intended behavior.