fix empty workspace

Signed-off-by: Hailong Cui <ihailong@amazon.com>

src/plugins/workspace/server/saved_objects/workspace_saved_objects_client_wrapper.ts

@@ -468,7 +468,7 @@ export class WorkspaceSavedObjectsClientWrapper {
           })
         ).saved_objects.map((item) => item.id);
 
-        if (options.workspaces) {
+        if (options.workspaces && options.workspaces.length > 0) {
           const permittedWorkspaces = options.workspaces.filter((item) =>
             permittedWorkspaceIds.includes(item)
           );