Image mosaic initialization can stop abruptly if one of the granule acceptors throws an exception

Point in case, the mosaic is given a set of Sentinel SAFE packges, containing JP2 but also a few non georeferenced images in png/jpeg. Also, coverage name collection is setup to create a multi-coverage mosaic out of the 13 band files.

When the mosaic stumbles into the non georeferenced images, the collection will stop there and eventually fail.