I tried to split a merged buffer chest, with request set. If I remove the request before splitting, things work as expected.

2919.258 Error MainLoop.cpp:1404: Exception at tick 199845105: The mod Merging Chests Logistic (2.0.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event WideChestsLogistic::Custom event (ID 301)
WideChestsLogistic/control.lua:9: attempt to index global 'entity_from' (a nil value)
stack traceback:
WideChestsLogistic/control.lua:9: in function 'move_logistic_requests'
WideChestsLogistic/control.lua:53: in function <WideChestsLogistic/control.lua:52>
stack traceback:
[C]: in function 'raise_event'
WideChests/scripts/event_handlers/split_chest.lua:3: in function 'raise_on_chest_split'
WideChests/scripts/event_handlers/split_chest.lua:47: in function <WideChests/scripts/event_handlers/split_chest.lua:33>

What value do you have for "Copy requests on split" mod setting in player tab?

And what requests did your merged chest have before the split?

The copy requests on split is the default of "Copy Requests". The request was for 160 stacks of the item, to fill the merged capacity.

Fixed in 2.0.1