I think "Ultracube: Age of Space" mod is incompatible with this one or vice versa, it crashed when picking up the cube item from the ground.

55551.051 Error MainLoop.cpp:1468: Exception at tick 7849060: The mod Assembly combinators (0.6.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event assembly-combinator::on_pre_player_mined_item (ID 15)
__assembly-combinator__/script/events.lua:15: table index is nil
stack traceback:
        __assembly-combinator__/script/events.lua:15: in function 'cleanup_entity'
        __assembly-combinator__/script/events.lua:24: in function <__assembly-combinator__/script/events.lua:23>

Thanks for the trace! I'll take a look

I managed to replicate and fix it, try version 0.6.1. I did something weird in my cleanup script which triggered when mining entities from other mods. Thanks for reporting it!