CmdPal: fix a crash on setting the same alias

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/AliasManager.cs

@@ -86,18 +86,24 @@ public partial class AliasManager : ObservableObject
             return;
         }
 
-        // If we already have _this exact alias_, do nothing
+        // Look for the old alias, and remove it
+        List<CommandAlias> toRemove = [];
+
         if (newAlias != null &&
             _aliases.TryGetValue(newAlias.SearchPrefix, out var existingAlias))
         {
             if (existingAlias.CommandId == commandId)
             {
+                // If we already have _this exact alias_, do nothing
                 return;
             }
+            else
+            {
+                // We have _something else_ bound to this alias. Remove it.
+                toRemove.Add(existingAlias);
+            }
         }
 
-        // Look for the old alias, and remove it
-        List<CommandAlias> toRemove = [];
         foreach (var kv in _aliases)
         {
             if (kv.Value.CommandId == commandId)

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/TopLevelViewModel.cs

@@ -137,11 +137,20 @@ public sealed partial class TopLevelViewModel : ObservableObject, IListItem
 
         item.PropertyChanged += Item_PropertyChanged;
 
+        _settings.SettingsChanged += SettingsChanged;
+
         // UpdateAlias();
         // UpdateHotkey();
         // UpdateTags();
     }
 
+    private void SettingsChanged(SettingsModel sender, object? args)
+    {
+        FetchAliasFromAliasManager();
+        UpdateHotkey();
+        UpdateTags();
+    }
+
     private void Item_PropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
     {
         if (!string.IsNullOrEmpty(e.PropertyName))
@@ -188,6 +197,12 @@ public sealed partial class TopLevelViewModel : ObservableObject, IListItem
                 // Decouple from the alias manager alias object
                 Alias = new CommandAlias(commandAlias.Alias, commandAlias.CommandId, commandAlias.IsDirect);
             }
+            else
+            {
+                Alias = null;
+            }
+
+            UpdateTags();
         }
     }