no UC_AFL_NO_RETURN attribute in Uc object

[cube0x8]

when running in debug mode, I get the following error:

File "/mnt/data/unicorefuzz/unicorefuzz/harness.py", line 232, in uc_debug
    if uc.afl_forkserver_start(exits) != uc.UC_AFL_RET_NO_AFL:
AttributeError: 'Uc' object has no attribute 'UC_AFL_RET_NO_AFL'
python-BaseException```