handle authentication failure in auth screen

web/repertory/lib/models/auth.dart

@@ -17,19 +17,37 @@ class Auth with ChangeNotifier {
   bool get authenticated => _authenticated;
   SecureKey get key => _key;
 
-  Future<void> authenticate(String user, String password) async {
-    final sodium = constants.sodium;
+  Future<bool> authenticate(String user, String password) async {
+    try {
+      final sodium = constants.sodium;
 
-    final keyHash = sodium.crypto.genericHash(
-      outLen: sodium.crypto.aeadXChaCha20Poly1305IETF.keyBytes,
-      message: Uint8List.fromList(password.toCharArray()),
-    );
+      final keyHash = sodium.crypto.genericHash(
+        outLen: sodium.crypto.aeadXChaCha20Poly1305IETF.keyBytes,
+        message: Uint8List.fromList(password.toCharArray()),
+      );
 
-    _authenticated = true;
-    _key = SecureKey.fromList(sodium, keyHash);
-    _user = user;
+      _key = SecureKey.fromList(sodium, keyHash);
+      _user = user;
 
-    notifyListeners();
+      final auth = await createAuth();
+      final response = await http.put(
+        Uri.parse(
+          Uri.encodeFull('${getBaseUri()}/api/v1/locations?auth=$auth'),
+        ),
+      );
+
+      _authenticated = (response.statusCode == 200);
+      if (_authenticated) {
+        notifyListeners();
+
+        return _authenticated;
+      }
+    } catch (e) {
+      debugPrint('$e');
+    }
+
+    logoff();
+    return false;
   }
 
   Future<String> createAuth() async {

web/repertory/lib/screens/auth_screen.dart

@@ -57,22 +57,26 @@ class _AuthScreenState extends State<AuthScreen> {
       }
 
       setState(() => _enabled = false);
-      await auth.authenticate(
+      var authenticated = await auth.authenticate(
         _userController.text.trim(),
         _passwordController.text,
       );
       setState(() => _enabled = true);
 
-      // if (!mounted) return;
-      //
-      // if (!(ok == true || auth.authenticated)) {
-      //   ScaffoldMessenger.of(context).showSnackBar(
-      //     const SnackBar(
-      //       content: Text('Invalid username or password'),
-      //       behavior: SnackBarBehavior.floating,
-      //     ),
-      //   );
-      // }
+      if (authenticated) {
+        return;
+      }
+
+      if (!context.mounted) {
+        return;
+      }
+
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(
+          content: Text('Invalid username or password'),
+          behavior: SnackBarBehavior.floating,
+        ),
+      );
     }
 
     void navigateHomePostFrame() {