Add error handling and validation for custom file manager paths

Flow.Launcher/Languages/en.xaml

@@ -373,6 +373,8 @@
     <system:String x:Key="fileManager_path">File Manager Path</system:String>
     <system:String x:Key="fileManager_directory_arg">Arg For Folder</system:String>
     <system:String x:Key="fileManager_file_arg">Arg For File</system:String>
+    <system:String x:Key="fileManagerPathNotFound">The path for the file manager '{0}' could not be found: {1}\n\nDo you want to continue?</system:String>
+    <system:String x:Key="fileManagerPathError">File Manager Path Error</system:String>
 
     <!--  DefaultBrowser Setting Dialog  -->
     <system:String x:Key="defaultBrowserTitle">Default Web Browser</system:String>
@@ -462,6 +464,10 @@
     <system:String x:Key="reportWindow_upload_log">1. Upload log file: {0}</system:String>
     <system:String x:Key="reportWindow_copy_below">2. Copy below exception message</system:String>
 
+    <!--  File Open Error  -->
+    <system:String x:Key="folderOpenError">An error occurred while opening the folder.:\n{0}</system:String>
+    <system:String x:Key="errorTitle">Error</system:String>
+
     <!--  General Notice  -->
     <system:String x:Key="pleaseWait">Please wait...</system:String>
 

Flow.Launcher/PublicAPIInstance.cs

@@ -316,40 +316,63 @@ namespace Flow.Launcher
 
         public void OpenDirectory(string DirectoryPath, string FileNameOrFilePath = null)
         {
-            using var explorer = new Process();
+            try
-            var explorerInfo = _settings.CustomExplorer;
+            {
-            var explorerPath = explorerInfo.Path.Trim().ToLowerInvariant();
+                using var explorer = new Process();
-            var targetPath = FileNameOrFilePath is null
+                var explorerInfo = _settings.CustomExplorer;
-                ? DirectoryPath
+                var explorerPath = explorerInfo.Path.Trim().ToLowerInvariant();
-                : Path.IsPathRooted(FileNameOrFilePath)
+                var targetPath = FileNameOrFilePath is null
-                    ? FileNameOrFilePath
+                    ? DirectoryPath
-                    : Path.Combine(DirectoryPath, FileNameOrFilePath);
+                    : Path.IsPathRooted(FileNameOrFilePath)
+                        ? FileNameOrFilePath
+                        : Path.Combine(DirectoryPath, FileNameOrFilePath);
 
-            if (Path.GetFileNameWithoutExtension(explorerPath) == "explorer")
+                if (Path.GetFileNameWithoutExtension(explorerPath) == "explorer")
-            {
-                // Windows File Manager
-                // We should ignore and pass only the path to Shell to prevent zombie explorer.exe processes
-                explorer.StartInfo = new ProcessStartInfo
                 {
-                    FileName = targetPath,         // Not explorer, Only path.
+                    // Windows File Manager
-                    UseShellExecute = true         // Must be true to open folder
+                    explorer.StartInfo = new ProcessStartInfo
-                };
+                    {
-            }
+                        FileName = targetPath,
-            else
+                        UseShellExecute = true
-            {
+                    };
-                // Custom File Manager
+                }
-                explorer.StartInfo = new ProcessStartInfo
+                else
                 {
-                    FileName = explorerInfo.Path.Replace("%d", DirectoryPath),
+                    // Custom File Manager
-                    UseShellExecute = true,
+                    explorer.StartInfo = new ProcessStartInfo
-                    Arguments = FileNameOrFilePath is null
+                    {
-                        ? explorerInfo.DirectoryArgument.Replace("%d", DirectoryPath)
+                        FileName = explorerInfo.Path.Replace("%d", DirectoryPath),
-                        : explorerInfo.FileArgument
+                        UseShellExecute = true,
-                            .Replace("%d", DirectoryPath)
+                        Arguments = FileNameOrFilePath is null
-                            .Replace("%f", targetPath)
+                            ? explorerInfo.DirectoryArgument.Replace("%d", DirectoryPath)
-                };
+                            : explorerInfo.FileArgument
+                                .Replace("%d", DirectoryPath)
+                                .Replace("%f", targetPath)
+                    };
+                }
+
+                explorer.Start();
+            }
+            catch (System.ComponentModel.Win32Exception ex) when (ex.NativeErrorCode == 2)
+            {
+                // File Manager not found
+                MessageBoxEx.Show(
+                    string.Format(GetTranslation("fileManagerNotFound"), ex.Message),
+                    GetTranslation("fileManagerNotFoundTitle"),
+                    MessageBoxButton.OK,
+                    MessageBoxImage.Error
+                );
+            }
+            catch (Exception ex)
+            {
+                // Other exceptions
+                MessageBoxEx.Show(
+                    string.Format(GetTranslation("folderOpenError"), ex.Message),
+                    GetTranslation("errorTitle"),
+                    MessageBoxButton.OK,
+                    MessageBoxImage.Error
+                );
             }
-            explorer.Start();
         }
 
         private void OpenUri(Uri uri, bool? inPrivate = null)

Flow.Launcher/SelectFileManagerWindow.xaml.cs

@@ -1,5 +1,8 @@
-using System.Collections.ObjectModel;
+using System;
+using System.Collections.ObjectModel;
 using System.ComponentModel;
+using System.Diagnostics;
+using System.IO;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
@@ -43,11 +46,62 @@ namespace Flow.Launcher
 
         private void btnDone_Click(object sender, RoutedEventArgs e)
         {
+            // Check if the selected file manager path is valid
+            if (!IsFileManagerValid(CustomExplorer.Path))
+            {
+                MessageBoxResult result = MessageBoxEx.Show(
+                    string.Format((string)Application.Current.FindResource("fileManagerPathNotFound"), 
+                        CustomExplorer.Name, CustomExplorer.Path),
+                    (string)Application.Current.FindResource("fileManagerPathError"),
+                    MessageBoxButton.YesNo,
+                    MessageBoxImage.Warning);
+
+                if (result == MessageBoxResult.No)
+                {
+                    return;
+                }
+            }
+
             _settings.CustomExplorerList = CustomExplorers.ToList();
             _settings.CustomExplorerIndex = SelectedCustomExplorerIndex;
             Close();
         }
 
+        private bool IsFileManagerValid(string path)
+        {
+            if (string.Equals(path, "explorer", StringComparison.OrdinalIgnoreCase))
+                return true;
+            
+            if (Path.IsPathRooted(path))
+            {
+                return File.Exists(path);
+            }
+
+            try
+            {
+                var process = new Process
+                {
+                    StartInfo = new ProcessStartInfo
+                    {
+                        FileName = "where",
+                        Arguments = path,
+                        RedirectStandardOutput = true,
+                        UseShellExecute = false,
+                        CreateNoWindow = true
+                    }
+                };
+                process.Start();
+                string output = process.StandardOutput.ReadToEnd();
+                process.WaitForExit();
+
+                return !string.IsNullOrEmpty(output);
+            }
+            catch
+            {
+                return false;
+            }
+        }
+
         private void btnAdd_Click(object sender, RoutedEventArgs e)
         {
             CustomExplorers.Add(new()