[0.6.0-rc1 QA] Client crash when name of user not logged into client (but logged into JI) changed

[rocodes]

Description

While performing QA, I changed the name of a user not logged into the client, but who was logged into the JI, and the client crashed while syncing.

Steps to Reproduce

I've tried to reproduce this a couple times and I can't.

• Log into JI web interface as admin user A. Ensure there are replies to sources from this user.
• Log into SDW client as journalist B.
• In the web client, change the name of admin user A

Expected Behavior

• Journalist A's messages in the client have their new initials

Actual Behavior

Client crash (client window disappears)
from sd-app:

Feb  1 18:11:44 localhost 2022-02-01 18:11:44,566 - root:63(excepthook) ERROR: Unrecoverable error#012Traceback (most recent call last):#012  File "/opt/venvs/securedrop-client/lib/python3.7/site-packages/securedrop_client/gui/widgets.py", line 2037, in _on_update_authenticated_user#012    if user.uuid == self.sender.uuid:#012AttributeError: 'NoneType' object has no attribute 'uuid'
Feb  1 18:11:44 localhost qubes.VMShell-dom0: Traceback (most recent call last):
Feb  1 18:11:44 localhost qubes.VMShell-dom0:   File "/opt/venvs/securedrop-client/lib/python3.7/site-packages/securedrop_client/gui/widgets.py", line 2037, in _on_update_authenticated_user
Feb  1 18:11:44 localhost qubes.VMShell-dom0:     if user.uuid == self.sender.uuid:
Feb  1 18:11:44 localhost qubes.VMShell-dom0: AttributeError: 'NoneType' object has no attribute 'uuid'

Comments

Suggestions to fix, any other relevant information.