The request that failed without receiving a response. The user still has a network connection, so we need to determine why the connection may have failed.
A Promise resolved when the diagnostics suite has completed. NOTE: {@link module:data/utils.withDiagnostics withDiagnostics} will proceed without waiting for this promise to resolve.
Invoked when a data call is aborted (Response status is 0) but the user has a connection to the Internet. NOTE: This method may be called multiple times; its logic should ensure it only runs diagnostics the desired number of times (e.g. once per failed domain). Also, this method is responsible for logging results (or for caching the results if a connection could not be established).