The mod Productions Per Minute (0.2.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event productions-per-minute::on_gui_opened (ID 95)
__productions-per-minute__/control.lua:42: bad argument #1 of 2 to 'pairs' (table expected, got nil)
stack traceback:
    [C]: in function 'pairs'
    __productions-per-minute__/control.lua:42: in function 'is_valid_gui_entity'
    __productions-per-minute__/control.lua:52: in function <__productions-per-minute__/control.lua:50>

should be the same issue with this one.
https://mods.factorio.com/mod/productions-per-minute/discussion/6724c4c2b1953ad0014f898d

May I lock this thread so we can keep track of it in one place