Fix pane enumeration and nullable parameter handling

- Fix GetAllLeafNodes to include tabbed panes and avoid duplicates
- Make logger parameter nullable in HostProfileManagerViewModel
- Make exception parameter nullable in Result.Failure methods

Author: tomertec

src/SshManager.App/Services/PaneLayoutManager.cs

@@ -373,12 +373,24 @@ public void CycleFocusPrevious()
     /// <inheritdoc />
     public IEnumerable<PaneLeafNode> GetAllLeafNodes()
     {
-        if (_rootNode == null)
-            yield break;
+        // Include tabbed panes (these may not be in the tree structure)
+        foreach (var tabbedPane in _tabbedPanes)
+        {
+            yield return tabbedPane;
+        }
 
-        foreach (var leaf in GetLeafNodesRecursive(_rootNode))
+        // Include tree panes if we have a root node
+        if (_rootNode != null)
         {
-            yield return leaf;
+            // Get all leaf nodes from tree, excluding any already returned as tabbed panes
+            var tabbedPaneIds = new HashSet<Guid>(_tabbedPanes.Select(p => p.Id));
+            foreach (var leaf in GetLeafNodesRecursive(_rootNode))
+            {
+                if (!tabbedPaneIds.Contains(leaf.Id))
+                {
+                    yield return leaf;
+                }
+            }
         }
     }
 

src/SshManager.App/ViewModels/HostProfileManagerViewModel.cs

@@ -33,11 +33,11 @@ public partial class HostProfileManagerViewModel : ObservableObject
     public HostProfileManagerViewModel(
         IHostProfileRepository profileRepository,
         IProxyJumpProfileRepository proxyJumpRepository,
-        ILogger<HostProfileManagerViewModel> logger)
+        ILogger<HostProfileManagerViewModel>? logger)
     {
         _profileRepository = profileRepository;
         _proxyJumpRepository = proxyJumpRepository;
-        _logger = logger;
+        _logger = logger ?? Microsoft.Extensions.Logging.Abstractions.NullLogger<HostProfileManagerViewModel>.Instance;
     }
 
     /// <summary>

src/SshManager.Core/Result.cs

@@ -70,12 +70,12 @@ public static Result<T> Failure(Exception exception) =>
         new(false, default, exception.Message, exception);
 
     /// <summary>
-    /// Creates a failed result with an error message and exception.
+    /// Creates a failed result with an error message and optional exception.
     /// </summary>
     /// <param name="error">The error message describing the failure.</param>
-    /// <param name="exception">The exception that caused the failure.</param>
+    /// <param name="exception">The exception that caused the failure, if any.</param>
     /// <returns>A failed result with both the error message and exception.</returns>
-    public static Result<T> Failure(string error, Exception exception) =>
+    public static Result<T> Failure(string error, Exception? exception) =>
         new(false, default, error, exception);
 
     /// <summary>
@@ -222,12 +222,12 @@ public static Result Failure(Exception exception) =>
         new(false, exception.Message, exception);
 
     /// <summary>
-    /// Creates a failed result with an error message and exception.
+    /// Creates a failed result with an error message and optional exception.
     /// </summary>
     /// <param name="error">The error message describing the failure.</param>
-    /// <param name="exception">The exception that caused the failure.</param>
+    /// <param name="exception">The exception that caused the failure, if any.</param>
     /// <returns>A failed result with both the error message and exception.</returns>
-    public static Result Failure(string error, Exception exception) =>
+    public static Result Failure(string error, Exception? exception) =>
         new(false, error, exception);
 
     /// <summary>