Throw an exception if the file system and the database are out of sync (see #5101)
Merge remote-tracking branch 'upstream/hotfix/3.0.4' into hotfix/3.0.4
Return `null` if a relation does not exist (see #5356)

If an eagerly loaded relation does not exist, return `null` instead of an empty model in `Model::getRelated()`.
Merge the latest version 2.11 changes
Updated all language files
Merge remote-tracking branch 'upstream/hotfix/3.0.4' into hotfix/3.0.4