Comment 3 for bug 1960934

relation.app is an Application instance during the broken hook but it has a blank name. I believe that the application-level relation data is also still available, but the way the framework tries to load the data, it ends up passing that empty name in to relation-get, leading to the error. I don't think that the charm / interface code actually needs that data, since it's really just checking whether the relation is valid or not. Perhaps this should be handled more gracefully in the framework; we can certainly work around it in the library but I've seen this edge case come up before in other charm code so it's probably worth handling it in the framework and just returning empty relation data to avoid the issue.