server is crashing after terraingen is turned off

[ruyxx]

works fine with disabling entities but when i disable terraingen it crashes and outputs this code
Current thread 0x00007f0ac1d78440 (most recent call first):
File "/home/ruyx/Desktop/cwsrv/cuwo/world.py", line 381 in create_entity
File "/home/ruyx/Desktop/cwsrv/cuwo/server.py", line 276 in on_entity_packet
File "/home/ruyx/Desktop/cwsrv/cuwo/server.py", line 260 in on_packet
File "/home/ruyx/Desktop/cwsrv/cuwo/packet.py", line 764 in feed
File "/home/ruyx/Desktop/cwsrv/cuwo/server.py", line 209 in data_received
File "/home/ruyx/.pyenv/versions/3.6.1/lib/python3.6/asyncio/selector_events.py", line 731 in _read_ready
File "/home/ruyx/.pyenv/versions/3.6.1/lib/python3.6/asyncio/events.py", line 127 in _run
File "/home/ruyx/.pyenv/versions/3.6.1/lib/python3.6/asyncio/base_events.py", line 1425 in _run_once
File "/home/ruyx/.pyenv/versions/3.6.1/lib/python3.6/asyncio/base_events.py", line 421 in run_forever
File "/home/ruyx/Desktop/cwsrv/cuwo/server.py", line 907 in main
File "/home/ruyx/Desktop/cwsrv/cuwo/server.py", line 915 in
File "/home/ruyx/.pyenv/versions/3.6.1/lib/python3.6/runpy.py", line 85 in _run_code
File "/home/ruyx/.pyenv/versions/3.6.1/lib/python3.6/runpy.py", line 193 in _run_module_as_main
/home/ruyx/Desktop/cwsrv/run_server.sh: line 10: 3516 Segmentation fault python -m cuwo.server