Error messages not meaningful

There is a way to get more detailed error output. In this example in this from saving the context after deleting a managed object in CoreData:

        NSError* error;
        if(![[survey managedObjectContext] save:&error]) {
                NSLog(@"Failed to save to data store: %@", [error localizedDescription]);
                NSArray* detailedErrors = [[error userInfo] objectForKey:NSDetailedErrorsKey];
                if(detailedErrors != nil && [detailedErrors count] > 0) {
                        for(NSError* detailedError in detailedErrors) {
                                NSLog(@"  DetailedError: %@", [detailedError userInfo]);
                        }
                }
                else {
                        NSLog(@"  %@", [error userInfo]);
                }
        }