sync_telegram, sync_viber: access error while leaving the channel

[trojikman]

Steps to reproduce the error:

1. Write to the bot
2. Receive the message in Odoo and go to Telegram/Viber channels through Discuss sidebar.
3. Press the Leave button
   As a result, you'll get "Access Error":
   

Also, when trying to send a new message to the bot the message in Odoo doesn't appear

Expected behavior:
Don't get an error and be able to receive messages from archived messages

[em230418]

via Hubstaff
User: Eugene Molotov

Project: sync-addons - https://app.hubstaff.com/projects/1618283
Date Range: 09/01/21 - 09/01/21
Work session total: 1:05:50
Billable: Yes

Grand total: 1:05:50

[trojikman]

via Hubstaff
User: Denis Mudarisov

Project: sync-addons - https://app.hubstaff.com/projects/1618283
Date Range: 09/02/21 - 09/02/21
Work session total: 0:16:40
Billable: Yes

Grand total: 2:35:18

[em230418]

via Hubstaff
User: Eugene Molotov

Project: sync-addons - https://app.hubstaff.com/projects/1618283
Date Range: 09/02/21 - 09/02/21
Work session total: 1:12:48
Billable: Yes

Grand total: 2:35:18

[em230418]

via Hubstaff
User: Eugene Molotov

Project: sync-addons - https://app.hubstaff.com/projects/1618283
Date Range: 09/07/21 - 09/07/21
Work session total: 0:56:57
Billable: Yes

Grand total: 3:32:15

[trojikman]

via Hubstaff
User: Denis Mudarisov

Project: sync-addons - https://app.hubstaff.com/projects/1618283
Date Range: 09/08/21 - 09/08/21
Work session total: 0:14:52
Billable: Yes

Grand total: 4:27:09

[em230418]

via Hubstaff
User: Eugene Molotov

Project: sync-addons - https://app.hubstaff.com/projects/1618283
Date Range: 09/08/21 - 09/08/21
Work session total: 0:40:02
Billable: Yes

Grand total: 4:27:09