Issue with previewing content in Sanity Studio and identifying the cause of the problem.

  document: {
    // For singleton types, filter out actions that are not explicitly included
    // in the `singletonActions` list defined above
    actions: (input, context) =>
      singletonTypes.has(context.schemaType)
        ? input.filter(({ action }) => action && singletonActions.has(action))
        : input,
  },