Module

mass_mailing_unique

Describe the bug

I installed odoo 16 CE with several apps, with demo records creation activated.
It created a bunch of mailing.contact records, with 3 of them not having email field defined.
Then when i tried to instal mass_mailing_unique, it complains about the existence of these 3 records having similar email: None
odoorpc.error.RPCError: Unable to install module mass_mailing_unique: There are 3 mailing contacts with the same email: None
I added a mail to the 3 mailing contacts that didn't have, then installation worked

To Reproduce

Version: Odoo 16 CE.

Steps to reproduce the behavior:

1. Try to create mass_mailing records with field 'email' not define
2. try to install mass_mailing_unique
3. Installation will fail.
4. Add email field to those records
5. Installation works
6. Once installed, you can create 2 records in mailing.contact with no email, mass_mailing_unique module won't complain.

Expected behavior
Records with email field not defined should not be considered by module mass_mailing_unique as having the same email, and prevent installation of the module.

Additional context
Odoo 16 CE docker image