display error if mount location is not found

web/repertory/lib/models/mount.dart

@@ -2,6 +2,7 @@ import 'dart:convert';
 
 import 'package:flutter/material.dart';
 import 'package:http/http.dart' as http;
+import 'package:repertory/constants.dart' as constants;
 import 'package:repertory/helpers.dart';
 import 'package:repertory/models/mount_list.dart';
 import 'package:repertory/types/mount_config.dart';
@@ -73,9 +74,9 @@ class Mount with ChangeNotifier {
     }
   }
 
-  Future<void> mount(bool unmount, {String? location}) async {
+  Future<bool> mount(bool unmount, {String? location}) async {
     try {
-      await http.post(
+      final response = await http.post(
         Uri.parse(
           Uri.encodeFull(
             '${getBaseUri()}/api/v1/mount?unmount=$unmount&name=$name&type=$type&location=$location',
@@ -83,10 +84,16 @@ class Mount with ChangeNotifier {
         ),
       );
 
-      return refresh();
+      if (response.statusCode == 500) {
+        return false;
+      }
+
+      await refresh();
     } catch (e) {
       debugPrint('$e');
     }
+
+    return true;
   }
 
   Future<void> refresh() async {

web/repertory/lib/widgets/mount_widget.dart

@@ -158,10 +158,23 @@ class _MountWidgetState extends State<MountWidget> {
 
                         mount
                             .mount(isActive, location: location)
-                            .then((_) {
+                            .then((success) {
                               setState(() {
                                 _enabled = true;
                               });
+
+                              if (isActive || !context.mounted) {
+                                return;
+                              }
+
+                              ScaffoldMessenger.of(context).showSnackBar(
+                                SnackBar(
+                                  content: const Text(
+                                    "Mount location not found",
+                                    textAlign: TextAlign.center,
+                                  ),
+                                ),
+                              );
                             })
                             .catchError((_) {
                               setState(() {