Merge pull request #16957 from owncloud/throw-exception-if-file-does-not-exist

apps/files_sharing/api/server2server.php

apps/files_sharing/lib/controllers/sharecontroller.php

apps/files_sharing/lib/helper.php

apps/files_sharing/lib/propagation/recipientpropagator.php

apps/files_sharing/lib/share/file.php

apps/files_sharing/tests/controller/sharecontroller.php

apps/files_sharing/tests/etagpropagation.php

apps/files_trashbin/lib/trashbin.php

apps/files_versions/lib/storage.php

apps/files_versions/tests/versions.php

lib/private/files/filesystem.php

lib/private/files/view.php

lib/private/hook.php

tests/lib/files/view.php