Currently, any failed request to the source Wiki will result in the target Wikibase entering an error state. This behavior is the case even in non-critical situations such as displaying property labels on the revision history page for an item. Please note when discussing this story that a similar issue exists on the Special:RecentChanges page and diff pages when the federation source wiki is unavailable.
If displaying federated properties is not possible when loading an edit summary due to a failed call to the source Wiki, then we should format the edit summaries differently, displaying only PIDs rather than displaying an error page.
**BDD**
`Given` My connection to the source Wiki is unavailable
`When` I load a revision history page, recent changes page, or diff page that involves statements with federated properties
`Then` the page loads without labels for the properties, just linked PIDs.
Note: This should be testable using ModHeader in the test system.