Empty exception while removing User from Group via Looker API

[Patrick_Chodows]

Hello,

We have automated process for requesting and creating user accounts through custom access forms. Our existing users can request new access to some models in Looker.  What happens under the hood is that we remove them from their existing user groups and add them to the new ones. I am using method 

client.delete_group_user(group_id, user_id) to remove user from group and it usually works as expected, but from time to time I receive an empty exception thrown by Looker API. User gets removed from the group with exception but without any explanation what happened. 

There is literally empty error message. Does anyone encounter this error before? Maybe any one has an idea why it can happen?