Plugins: Fix API sync error handling (#113240)

apps/plugins/pkg/app/install/registrar.go

@@ -93,6 +93,7 @@ func equalStringPointers(a, b *string) bool {
 type InstallRegistrar struct {
 	clientGenerator resource.ClientGenerator
 	client          *pluginsv0alpha1.PluginClient
+	clientErr       error
 	clientOnce      sync.Once
 }
 
@@ -107,20 +108,21 @@ func (r *InstallRegistrar) GetClient() (*pluginsv0alpha1.PluginClient, error) {
 	r.clientOnce.Do(func() {
 		client, err := pluginsv0alpha1.NewPluginClientFromGenerator(r.clientGenerator)
 		if err != nil {
+			r.clientErr = err
 			r.client = nil
 			return
 		}
 		r.client = client
 	})
 
-	return r.client, nil
+	return r.client, r.clientErr
 }
 
 // Register creates or updates a plugin install in the registry.
 func (r *InstallRegistrar) Register(ctx context.Context, namespace string, install *PluginInstall) error {
 	client, err := r.GetClient()
 	if err != nil {
-		return nil
+		return err
 	}
 	identifier := resource.Identifier{
 		Namespace: namespace,
@@ -132,9 +134,12 @@ func (r *InstallRegistrar) Register(ctx context.Context, namespace string, insta
 		return err
 	}
 
-	if existing != nil && install.ShouldUpdate(existing) {
-		_, err = client.Update(ctx, install.ToPluginInstallV0Alpha1(namespace), resource.UpdateOptions{ResourceVersion: existing.ResourceVersion})
-		return err
+	if existing != nil {
+		if install.ShouldUpdate(existing) {
+			_, err = client.Update(ctx, install.ToPluginInstallV0Alpha1(namespace), resource.UpdateOptions{ResourceVersion: existing.ResourceVersion})
+			return err
+		}
+		return nil
 	}
 
 	_, err = client.Create(ctx, install.ToPluginInstallV0Alpha1(namespace), resource.CreateOptions{})
@@ -155,6 +160,10 @@ func (r *InstallRegistrar) Unregister(ctx context.Context, namespace string, nam
 	if err != nil && !errorsK8s.IsNotFound(err) {
 		return err
 	}
+	// if the plugin doesn't exist, nothing to unregister
+	if existing == nil {
+		return nil
+	}
 	// if the source is different, do not unregister
 	if existingSource, ok := existing.Annotations[PluginInstallSourceAnnotation]; ok && existingSource != source {
 		return nil