[HOTFIX] media selection page save none exist media, media selection collection filter

 - fix save error when media not exist
 - fix all images are shown when filter for collection

__Tasks:__

- [ ] test coverage
- [ ] gather feedback for my changes
- [ ] submit changes to the documentation
- [ ] ... <add your own tasks>


__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | [yes|no => <WHY?>]
| Fixed tickets | fixes #512 fixes #550 
| BC Breaks     | none
| Doc           | none
@alexander-schranz this is not a nice solution but if it works its ok for a hotfix! i will take a look for a better solution today!