I forced it to work with 1.1 to see what would happen. Any idea if it is an easy fix?

The mod Merging Chests (3.1.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event WideChests::on_lua_shortcut (ID 34)
LuaPlayer doesn't contain key clean_cursor.
stack traceback:
[C]: in function 'index'
__WideChests/control.lua:330: in function <WideChests/control.lua:327>

I fixed it... for better or worse it works now...

function MergingChests.OnShortCut(event)
if event.prototype_name == "merge-chest-selector" then
local player = game.players[event.player_index]
--if player.clean_cursor() then
local stack = player.cursor_stack
if player.cursor_stack and stack.can_set_stack({ name = "merge-chest-selector" }) then
stack.set_stack({ name = "merge-chest-selector" })
end
--end
end
end

Thanks for the report, I'll fix it asap

Thank you very much, love this mod <3