I guess you have some functions that manipulates the calls to the database.
You can wrap the calls to these functions with try-catch block and intercept all javax.persistence.PersistenceException.
If you need more specific data on the nature of the problem, I believe you can look at the cause and cast the underlying exception to some EclipseLink object.
Then, you can decide whether to report something to the log or just print nice message to the user.
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