Error when accessing a preview link if enabled_entity_types configuration is missing

applied #3 patch. issue is fixed now. and created MR.

Thanks abhishek_gupta1. My patch also fixed the settings form.

In what scenario would this be missing

If a module can't rely on the presence of config it installed something is wrong

The settings form has been added recently. When the form is saved with no entities selected then the configuration is deleted by:
$config->clear('enabled_entity_types');

This should be:
$config->set('enabled_entity_types', []);

Yes you're correct.
Can we get a post update hook to set NULL to [] in the config and remove the null handling?
We should fix broken config instead of babysitting it.

Thank you!