error log message for mismatched accessions is not very helpful

[graykr]

For example:

Repository Mismatch Between Resource -- Accession: 336 [ /repositories/3/ ] / [ /repositories/2/accessions/97 ]

This was quite difficult to debug. The number listed is the last component of the record series number, 85/1/336 and the first repository URI is for the American Law Libraries Association Archives (no longer held by UIUC) and the second combines the URI for the ALA Archives repository with the accession's URI. To figure this out, I had to go to https://staff.archivesspace-dev.library.illinois.edu/accessions/97

The error message would be improved if it had more text to explain what it was outputting and also included the Archon id for the collection rather than only the last component of the records series number.

message = "Repository Mismatch Between Resource -- Accession: " +
         arId + " [ " + recordRepoURI + " ] / [ " + accessionURI + " ]\n";

https://github.com/archivesspace/archon-migration/blob/5ab5bc4aed3607a71923ec91e0a515680c361f7b/src/org/nyu/edu/dlts/utils/ASpaceCopyUtil.java#L2287-L2288

message = "Repository Mismatch Between Resource -- Accession (for collection with Archon ID: " + dbId +
         "); Resource Repository URI [ "+ recordRepoURI + " ] / Accession URI [ " + accessionURI + " ]\n";

(arId is just the last component of the record series number (also known as the identifier in Archon) whereas dbId is the number in the URL in Archon)