fix: crashing when trying to open context menu of a commit that contains a invalid remote branch decorator (#2367)

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/Views/Histories.axaml.cs

@@ -1488,6 +1488,9 @@ private void FillOtherLocalBranchMenu(ContextMenu menu, ViewModels.Repository re
 
         private void FillRemoteBranchMenu(ContextMenu menu, ViewModels.Repository repo, Models.Branch branch, Models.Branch current, bool merged)
         {
+            if (branch == null)
+                return;
+
             var name = branch.FriendlyName;
 
             var submenu = new MenuItem();