Description:
Inserters (with >1 stack size) which are passing directly to each other can get stuck due to a damaged item (ie turret, wall etc).
This can happen when the damaged item is placed on the ground by the first inserter, the second inserter grabs it, and then the first inserter then delivers additional undamaged items of the same type to the square before the second inserter finishes waiting for additional items.
This bug seems fairly rare in normal play as the timing is quite difficult to pull off, I've mostly seen it after power issues slow down one of the inserters.
Repro:
I was able to find a timing agnostic repro (included in the attached save).
1) Place two inserters with stack size >1 so they pass directly to each other (make sure they are both unpowered).
2) Place a damaged turret (or wall etc) on the ground between the inserters.
3) Provide a stack of undamaged turrets to the first inserter to grab.
4) Power only the first inserter, it should grab some undamaged turrets and attempt to place them on the ground between the two inserters, but be blocked by the damaged turret.
5) Power both inserters. The second inserter should grab the damaged turret, but will get stuck (probably trying to pick up the undamaged turrets to fill its capacity?)
