Added a guard against iterating over None in stats.views.document_stats()

 - Legacy-Id: 14250

Author: levkowetz

ietf/stats/views.py

@@ -676,8 +676,9 @@ def generate_canonical_names(docalias_qs):
                     country_name = aliases.get(country, country)
                     c = countries.get(country_name)
 
-                    if country_name:
-                        for year in doc_years.get(doc):
+                    years = doc_years.get(doc)
+                    if country_name and years:
+                        for year in years:
                             if years_from <= year <= years_to:
                                 bins[(year, country_name)].add(name)