feature: enhance the behaviour of closing the last tab

* If the last tab is an opened repository, go back to the welcome page
* If the last tab is welcome page, quit this app

src/ViewModels/Launcher.cs

@@ -107,7 +107,22 @@ namespace SourceGit.ViewModels
         {
             if (Pages.Count == 1)
             {
-                App.Quit();
+                var last = Pages[0];
+                if (last.Data is Repository repo)
+                {
+                    Commands.AutoFetch.RemoveRepository(repo.FullPath);
+                    repo.Close();
+
+                    last.Node = new RepositoryNode() { Id = Guid.NewGuid().ToString() };
+                    last.Data = new Welcome();
+
+                    GC.Collect();
+                }
+                else
+                {
+                    App.Quit();
+                }
+
                 return;
             }
 

src/ViewModels/LauncherPage.cs

@@ -26,13 +26,7 @@ namespace SourceGit.ViewModels
 
         public LauncherPage()
         {
-            _node = new RepositoryNode()
+            _node = new RepositoryNode() { Id = Guid.NewGuid().ToString() };
-            {
-                Id = Guid.NewGuid().ToString(),
-                Name = "WelcomePage",
-                Bookmark = 0,
-                IsRepository = false,
-            };
             _data = new Welcome();
         }