backend: fix unknown account code error after removing device

This fixed unknown account code error described in last commit.

The frontend got notified in wrong order when a device is removed.
The keystore event was pushed before accounts have been removed,
leading to a short moment when the frontend thinks it has accounts
but no more keystore.

Changed order so that the backend sends the keystore event after
accounts are uninitialized.

Author: thisconnect

backend/backend.go

@@ -549,16 +549,17 @@ func (backend *Backend) DeregisterKeystore() {
 	fingerprint, _ := backend.keystore.RootFingerprint()
 	backend.log.WithField("rootFingerprint", fingerprint).Info("deregistering keystore")
 	backend.keystore = nil
-	backend.Notify(observable.Event{
-		Subject: "keystores",
-		Action:  action.Reload,
-	})
 
 	backend.uninitAccounts()
 	// TODO: classify accounts by keystore, remove only the ones belonging to the deregistered
 	// keystore. For now we just remove all, then re-add the rest.
 	backend.initPersistedAccounts()
 	backend.emitAccountsStatusChanged()
+
+	backend.Notify(observable.Event{
+		Subject: "keystores",
+		Action:  action.Reload,
+	})
 }
 
 // Register registers the given device at this backend.