Fix unneccessary plugin result update

Author: Jack251970

Flow.Launcher.Core/ExternalPlugins/PluginsManifest.cs

@@ -27,12 +27,16 @@ public static async Task UpdateManifestAsync(CancellationToken token = default,
             {
                 await manifestUpdateLock.WaitAsync(token).ConfigureAwait(false);
 
-                if (UserPlugins == null || UserPlugins.Count == 0 || usePrimaryUrlOnly || DateTime.Now.Subtract(lastFetchedAt) >= fetchTimeout)
+                if (UserPlugins == null || usePrimaryUrlOnly || DateTime.Now.Subtract(lastFetchedAt) >= fetchTimeout)
                 {
                     var results = await mainPluginStore.FetchAsync(token, usePrimaryUrlOnly).ConfigureAwait(false);
 
-                    UserPlugins = results;
-                    lastFetchedAt = DateTime.Now;
+                    // If the results are empty, we shouldn't update the manifest because the results are invalid.
+                    if (results.Count != 0)
+                    {
+                        UserPlugins = results;
+                        lastFetchedAt = DateTime.Now;
+                    }
                 }
             }
             catch (Exception e)

Flow.Launcher/SettingPages/ViewModels/SettingsPanePluginStoreViewModel.cs

@@ -13,8 +13,8 @@ public partial class SettingsPanePluginStoreViewModel : BaseModel
 {
     public string FilterText { get; set; } = string.Empty;
 
-    public IList<PluginStoreItemViewModel> ExternalPlugins => PluginsManifest.UserPlugins
-        .Select(p => new PluginStoreItemViewModel(p))
+    public IList<PluginStoreItemViewModel> ExternalPlugins => 
+        PluginsManifest.UserPlugins?.Select(p => new PluginStoreItemViewModel(p))
         .OrderByDescending(p => p.Category == PluginStoreItemViewModel.NewRelease)
         .ThenByDescending(p => p.Category == PluginStoreItemViewModel.RecentlyUpdated)
         .ThenByDescending(p => p.Category == PluginStoreItemViewModel.None)