Fix errors with:
File "/app/python/lib/python3.5/site-packages/pdfminer/pdfinterp.py", line 850, in process_page
self.render_contents(page.resources, page.contents, ctm=ctm)
File "/app/python/lib/python3.5/site-packages/pdfminer/pdfinterp.py", line 860, in render_contents
self.init_resources(resources)
File "/app/python/lib/python3.5/site-packages/pdfminer/pdfinterp.py", line 360, in init_resources
self.fontmap[fontid] = self.rsrcmgr.get_font(objid, spec)
File "/app/python/lib/python3.5/site-packages/pdfminer/pdfinterp.py", line 210, in get_font
font = self.get_font(None, subspec)
File "/app/python/lib/python3.5/site-packages/pdfminer/pdfinterp.py", line 201, in get_font
font = PDFCIDFont(self, spec)
File "/app/python/lib/python3.5/site-packages/pdfminer/pdffont.py", line 667, in __init__
BytesIO(self.fontfile.get_data()))
File "/app/python/lib/python3.5/site-packages/pdfminer/pdftypes.py", line 297, in get_data
self.decode()
File "/app/python/lib/python3.5/site-packages/pdfminer/pdftypes.py", line 278, in decode
if 'Predictor' in params:
TypeError: argument of type 'NoneType' is not iterable