Handle NoneType to str

app/models.py

@@ -127,12 +127,12 @@ class Range(models.Model):
         db_table = 'range'
 
     def __str__(self):
-        return self.range_name if self else '--'
+        return self.range_name if self and self.range_name else '--'
 
     def dict(self):
         return {
             'id': self.id,
-            'name': self.name,
+            'name': self.range_name,
             'gmba_id': self.gmba_id,
             'countries': self.countries,
         }