Showing a dialog with the error when branch creation fails

Author: StanleyGoldman

src/UnityExtension/Assets/Editor/GitHub.Unity/UI/BranchesView.cs

@@ -3,6 +3,7 @@
 using System.Linq;
 using UnityEditor;
 using UnityEngine;
+using Debug = System.Diagnostics.Debug;
 
 namespace GitHub.Unity
 {
@@ -17,6 +18,7 @@ class BranchesView : Subview
         private const string NewBranchConfirmButton = "Create";
         private const string FavoritesSetting = "Favorites";
         private const string FavoritesTitle = "Favorites";
+        private const string CreateBranchTitle = "Create branch";
         private const string LocalTitle = "Local branches";
         private const string RemoteTitle = "Remote branches";
         private const string CreateBranchButton = "New Branch";
@@ -500,7 +502,21 @@ private void OnCreateGUI()
                     if (createBranch)
                     {
                         GitClient.CreateBranch(newBranchName, selectedNode.Name)
-                            .FinallyInUI((success, e) => { if (success) Refresh(); })
+                            .FinallyInUI((success, e) => {
+                                     if (success)
+                                     {
+                                         Refresh();
+                                     }
+                                     else
+                                     {
+                                         var errorHeader = "fatal: ";
+                                         var errorMessage = e.Message.StartsWith(errorHeader) ? e.Message.Remove(0, errorHeader.Length) : e.Message;
+
+                                         EditorUtility.DisplayDialog(CreateBranchTitle,
+                                             errorMessage,
+                                             Localization.Cancel);
+                                     }
+                            })
                             .Start();
                     }