File loading exceptions, other than in concept file, are logged but not thrown.

[kaicode]

The concept file is loaded in the main thread. If there is an issue loading the file, for example a missing file header, an exception is thrown from the ReleaseImporter class. However all other files are loaded in threads and any loading errors do not cause an exception to be thrown. This means that there is no way for an implementation to know if the complete content has been loaded or not.