00:03:43: ERROR[EmergeThread]: ERROR: An unhandled exception occurred: LuaError: error: ...test/mods/minetest/technic-master/technic/rubber.lua:111: attempt to call method 'spawn_tree' (a nil value)
00:03:43: ERROR[EmergeThread]: stack traceback:

In thread 7ffe30832700:
/build/buildd/minetestc55-0.4.4/src/server.cpp:405: virtual void* EmergeThread::Thread(): Assertion '0' failed.
Debug stacks:
DEBUG STACK FOR THREAD 7ffe30832700:
#0  virtual void* EmergeThread::Thread()
(Leftover data: #1  virtual MapBlock* ServerMap::emergeBlock(v3s16, bool): p=(-77,-2,33), allow_generate=0)
(Leftover data: #2  ServerMapSector* ServerMap::createSector(v2s16): p2d=(-77,33))