The mod Will-o'-the-Wisps Unofficial Fork (0.3.29) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Will-o-the-Wisps_Unofficial_Fork::on_nth_tick(3607)
LuaCommandable doesn't contain key commandable.
stack traceback:
[C]: in function 'index'
__Will-o-the-Wisps_Unofficial_Fork/control.lua:560: in function '?'
Will-o-the-Wisps_Unofficial_Fork/control.lua:744: in function 'run_periodic_task'
Will-o-the-Wisps_Unofficial_Fork/control.lua:779: in function <Will-o-the-Wisps_Unofficial_Fork/control.lua:760>

I saw the same:

The mod Will-o'-the-Wisps Unofficial Fork (0.3.29) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Will-o-the-Wisps_Unofficial_Fork::on_nth_tick(3607)
LuaCommandable doesn't contain key commandable.
stack traceback:
    [C]: in function '__index'
    __Will-o-the-Wisps_Unofficial_Fork__/control.lua:560: in function '?'
    __Will-o-the-Wisps_Unofficial_Fork__/control.lua:744: in function 'run_periodic_task'
    __Will-o-the-Wisps_Unofficial_Fork__/control.lua:779: in function <__Will-o-the-Wisps_Unofficial_Fork__/control.lua:760>

on the same tick? is it some kind of overflow bug?

No, just mis-use of a Lua API. The fix was easy: https://mods.factorio.com/mod/Will-o-the-Wisps-4