NPE when trying to create the Mets file for an AIP

[006627]

If an AIP has a submission but no schema, the NPE happens.

Possibly the problem is in the following method

commons-ip/src/main/java/org/roda_project/commons_ip2/model/impl/eark/EARKMETSUtils.java

Line 609 in 4892aa6

private static void addCommonFileGrpToMets(final MetsWrapper metsWrapper, final FileSec fileSec,