Fix bug due to 0 overall citations (close #301)

Author: Michael-E-Rose

pybliometrics/scopus/abstract_citation.py

@@ -43,7 +43,7 @@ def cc(self) -> List[List[Tuple[int, int]]]:
         for doc in self._citeInfoMatrix:
             try:
                 cites = [int(d['$']) for d in doc['cc']]
-            except AttributeError:  # No citations
+            except (AttributeError, TypeError):  # No citations
                 cites = [0]*len(_years)
             outer.append(list(zip(_years, cites)))
         return _maybe_return_list(outer)