[REFACTOR] Fix age property in profile model

backend/main/models.py

@@ -93,6 +93,8 @@ class Profile(models.Model):
 
     @property
     def age(self):
+        if self.birthdate is None:
+            return 0
         born = self.birthdate
         today = date.today()
         return today.year - born.year - ((today.month, today.day) < (born.month, born.day))