Fix crash

tournaments/models/tournament.py

@@ -690,6 +690,7 @@ class Tournament(models.Model):
 
         # all started matches have ended, possibly
         last_finished_match = self.last_finished_match()
+        if last_finished_match:
             # print(f'last_finished_match = {last_finished_match.name}')
             round_root_index = last_finished_match.round.root_round().index
             # print(f'round_index = {round_root_index}')
@@ -701,6 +702,8 @@ class Tournament(models.Model):
                     return round
                 else:
                     return None
+        else:
+            return None
 
     def last_started_match(self):
         matches = [m for m in self.all_matches(False) if m.start_date]