Do not fail hard if no appinfo is returned during update

[juliusknorr]

Fix for #8964

Before that the updater was failing hard when the appinfo of an enabled app could not been fetched. Now we just disable that app and continue.

Steps to reproduce:

1. Enable some app
2. Delete the appinfo.xml file from the app
3. Increase server version to trigger update
4. Try to update

[kyrofa]

This changes the upgrade error that I see, but I'm still getting an error (upgrading from 13.0.1 to this PR):

Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Nextcloud or one of the apps require upgrade - only a limited number of commands are available
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: You may use your browser or the occ upgrade command to do the upgrade
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Set log level to debug
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Turned on maintenance mode
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Updating database schema
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Updated database
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: UnexpectedValueException: The files of the app "activity" were not correctly replaced before running the update
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Update failed
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Maintenance mode is kept active
Mar 28 11:15:38 Pandora nextcloud.apache[8773]: Reset log level

I suppose it makes sense given this PR, but I don't really know what it means. Should that app have been disabled instead?

[nickvergessen]

Should that app have been disabled instead?

No, you need to ensure that you uploaded the new update correctly and that all files are readable by the www-data user

[MorrisJobke]

No, you need to ensure that you uploaded the new update correctly and that all files are readable by the www-data user

That is caused because it is a shipped app and you deleted one of it's files. Thus we know that there happened something bad. For other apps we are not that confident and thus just disable them. (just for the background of this.

Shipped apps are defined in here:

https://github.com/nextcloud/server/blob/master/core/shipped.json#L2-L37

If you remove the line with "activity" then the upgrade should run and disable the activity app.

[MorrisJobke]

Tested and works 👍