Major Description
The issue is that we came across a ReplicaNotFoundException in a bug report, the most informative thing we could get is "Replica not found for [ExtendedBlock]". If someone tries to investigate cases including ReplicaNotFoundExceptions should review diagnostic bundles, dig through logs, but as a starting point enhancing the exception message would boost this process, and be beneficial in the long run.
More concretely, it would be helpful if any of the following information was displayed along with the exception: file's name, replication factor or block location.