Minetest server crash

by player MilanFIN, damage 0 hp, health now 10 hp
22:38:26: ACTION[ServerThread]: MilanFIN punches object 3: LuaEntitySAO at (99.5819,41.25,-290.723)
22:38:26: ACTION[ServerThread]: LuaEntitySAO at (99.5819,41.25,-290.723) punched by player MilanFIN, damage 1 hp, health now 9 hp
22:38:28: ACTION[ServerThread]: MilanFIN punches object 25: LuaEntitySAO at (98.4726,41.25,-293.605)
22:38:28: ACTION[ServerThread]: LuaEntitySAO at (98.4726,41.25,-293.605) punched by player MilanFIN, damage 1 hp, health now 9 hp
22:38:29: ACTION[ServerThread]: MilanFIN punches object 9: LuaEntitySAO at (102.4,41.25,-294.788)
22:38:29: ACTION[ServerThread]: LuaEntitySAO at (102.4,41.25,-294.788) punched by player MilanFIN, damage 1 hp, health now 9 hp
22:38:32: ACTION[ServerThread]: MilanFIN punches object 6: LuaEntitySAO at (103.228,41.25,-287.006)
22:38:32: ACTION[ServerThread]: LuaEntitySAO at (103.228,41.25,-287.006) punched by player MilanFIN, damage 1 hp, health now 9 hp
22:38:33: ACTION[ServerThread]: MilanFIN punches object 16: LuaEntitySAO at (103.742,41.25,-284.161)
22:38:33: ACTION[ServerThread]: LuaEntitySAO at (103.742,41.25,-284.161) punched by player MilanFIN, damage 1 hp, health now 9 hp
22:38:33: ERROR[ServerThread]: ANIMALS: trying to activate animal sheep_naked at invalid position
22:38:33: ERROR[ServerThread]: 	Activation at: flowers:flower_viola --> removing
22:38:33: ERROR[ServerThread]: ANIMALS: No spawning information available on saving animal
22:38:33: ERROR[main]: ANIMALS: No spawning information available on saving animal
22:38:34: ERROR[main]: ERROR: An unhandled exception occurred: ServerError: LuaError: error running function 'on_punch': ...st-a35e4bd/bin/../mods/minetest/animals/spawning.lua:192: attempt to index field 'dynamic_data' (a nil value)
22:38:34: ERROR[main]: stack traceback:

In thread b77686d0:
/home/serverikone/celeron55-minetest-a35e4bd/src/main.cpp:1726: int main(int, char**): Assertion '0' failed.
Debug stacks:
DEBUG STACK FOR THREAD b77686d0:
#0  int main(int, char**)
(Leftover data: #1  Dedicated server branch)
(Leftover data: #2  virtual void ServerMap::save(ModifiedState))
(Leftover data: #3  virtual void ServerMap::saveBlock(MapBlock*))
(Leftover data: #4  void ItemStack::serialize(std::ostream&) const)
Keskeytetty (this means that the program have stopped!)