Fix crash

tournaments/models/tournament.py

@@ -549,7 +549,7 @@ class Tournament(models.Model):
     def last_started_match(self):
         matches = [m for m in self.all_matches(False) if m.start_date]
         matches.sort(key=lambda m: m.start_date, reverse=True)
-        return matches[0]
+        return matches.get(0) # get returns None if not present
 
     def round_for_index(self, index):
         return self.round_set.filter(index=index, parent=None).first()