When thumbnailing crashes, the library will try to over and over again, so you can never use the app ever again
Let's say you have a media that crashes the decoder when thumbnailing, the app containing the medialibrary will crash. If you relaunch the app, it found that there is no thumbnail, so it will try again to thumbnail it so it will crash again. This story never ends - unless you replicate MediaLibraryKit's behavior not to try to thumbnail a file again if that led to a crash in the past. Here, my story ends.
See also: VLCMediaLibraryKit#16 (closed)