server crash: attempt to perform arithmetic on upvalue 'duration' (a nil value)

[superfloh247]

minetest: latest master
paleotest: latest master

2021-04-25 13:47:23: ERROR[Main]: ServerError: AsyncErr: ServerThread::run Lua: Runtime error from mod '??' in callback luaentity_Step(): /opt/minetest/bin/../mods/paleotest/api/hq_lq.lua:408: attempt to perform arithmetic on upvalue 'duration' (a nil value)
2021-04-25 13:47:23: ERROR[Main]: stack traceback:
2021-04-25 13:47:23: ERROR[Main]: /opt/minetest/bin/../mods/paleotest/api/hq_lq.lua:408: in function 'func'
2021-04-25 13:47:23: ERROR[Main]: /opt/minetest/bin/../mods/mobkit/init.lua:621: in function 'execute_queues'
2021-04-25 13:47:23: ERROR[Main]: /opt/minetest/bin/../mods/mobkit/init.lua:848: in function 'stepfunc'
2021-04-25 13:47:23: ERROR[Main]: /opt/minetest/bin/../mods/paleotest/api/api.lua:88: in function 'old_step'
2021-04-25 13:47:23: ERROR[Main]: /opt/minetest/bin/../mods/paleotest/api/register.lua:53: in function </opt/minetest/bin/../mods/paleotest/api/register.lua:52>