TypeError: unsupported operand type(s) for -: 'NoneType' and 'int'

[simontimmins]

I have been running IDR on some samples and kept getting the error mentioned in #54, and solved this suing their solution. However I now receive the following error:
Traceback (most recent call last):
File ".local/bin/idr", line 4, in
import('pkg_resources').run_script('idr==2.0.2', 'idr')
File "/exports/applications/apps/SL7/anaconda/5.0.1/lib/python3.6/site-packages/pkg_resources/init.py", line 748, in run_script
self.require(requires)[0].run_script(script_name, ns)
File "/exports/applications/apps/SL7/anaconda/5.0.1/lib/python3.6/site-packages/pkg_resources/init.py", line 1517, in run_script
exec(code, namespace, namespace)
File "/exports/eddie3_homes_local/s2559269/.local/lib/python3.6/site-packages/idr-2.0.2-py3.6-linux-x86_64.egg/EGG-INFO/scripts/idr", line 10, in
idr.idr.main()
File ".local/lib/python3.6/site-packages/idr-2.0.2-py3.6-linux-x86_64.egg/idr/idr.py", line 774, in main
useBackwardsCompatibleOutput=args.use_old_output_format)
File ".local/lib/python3.6/site-packages/idr-2.0.2-py3.6-linux-x86_64.egg/idr/idr.py", line 433, in write_results_to_file
merged_peak, IDR, localIDR, output_file_type, signal_type)
File ".local/lib/python3.6/site-packages/idr-2.0.2-py3.6-linux-x86_64.egg/idr/idr.py", line 300, in build_idr_output_line_with_bed6
mean(x.summit-x.start for x in m_pk.pks[key+1])
File ".local/lib/python3.6/site-packages/idr-2.0.2-py3.6-linux-x86_64.egg/idr/idr.py", line 15, in mean
items = list(items)
File ".local/lib/python3.6/site-packages/idr-2.0.2-py3.6-linux-x86_64.egg/idr/idr.py", line 300, in
mean(x.summit-x.start for x in m_pk.pks[key+1])
TypeError: unsupported operand type(s) for -: 'NoneType' and 'int'

I still get IDR results but I am worried they may be affected in some way. Any advice would be appreciated!