Whilst playing I've received on multiple occasions the following error message.

"The mod Modular chests (2.0.13) caused a non-recoverable error.
Please report this error to mod author.

Error while running event LB-Modular-Chests::on_robot_built_entity (ID18)
LB-Modular-chests/control.lua:75:attemptto index field 'last_user' (a nil value)
Stack traceback:
LB-Modular-chests/control.lua:75: in function 'HandlePlacedEntity'
LB-Modular-chests/control.lua:6: in function
LB-Modular-chests/control.lua:5>

Any ideas why ?

When a new chest is placed, it is trying to access the user/robot that placed it, but for some reason it is not placed by anyone/anything.

Do you know how exactly they are being placed when the error occurs? Anything out of the ordinary? Is it not placed by a player or a robot?
Are you using any other mods to place down the chest?
Are you placing a 1x1 chest, or longer chests that are spawned in as items?

Thanks for the quick response and the amazing mod.

At the time a robot would have been placing it as each time I was else where on the map, they would have been placing a 1 x 1 as part of a bigger chest.
Other mods enabled but none that should place the chest.