Preconditions:

Created folder structure under Media folder
   root folder: zxcv
             child: zxcv01
             child: zxcv02
             child: zxcv03     

Steps to reproduce

1. Log in to back office.
2. Go to Content / Media.
3. Start creating an Image content.
4. In richtext field 'Caption' input an image file to trigger image picker.
5. Being on image-picker create folder structure as mentioned in preconditions.
6. Upload some image files to child folder 'zxcv02'.
7. Select child folder 'zxcv02'.
8. Delete root folder (send it to trash).

Actual result:

The folders structure has been removed and is no longer displayed in content-tree but on image list view, child folder name is still visible.

Expected result:

After removing folder structure, Media folder should be selected and all images from folder structures under Media folder should be displayed.