Auto generate thumbnail when don't have metadata on thetvdb

I want you to auto generate thumbnail of each episode when it don’t have episode’s image on thetvdb.
For example, this series https://www.thetvdb.com/?tab=season&seriesid=284041&seasonid=591797&lid=7
It doesn’t have any episode image. Instead, you will generate them for each. You just use fanart to replace it.

Please consider and solve them in the next version.
Thank.