Joi.external() error message

[ShyeChern]

Support plan

• is this issue currently blocking your project? (yes/no): no
• is this issue affecting a production system? (yes/no): no

Context

• node version: 14.11.0
• module version: 17.4
• environment (e.g. node, browser, native): node
• used with (e.g. hapi application, another framework, standalone, ...): standalone
• any other relevant information: Using this external API https://joi.dev/api/?v=17.4.0#anyexternalmethod-description

How can we help?

Scenario: When user submit input, I will check is it the user id exist in the database. If not exist it will return a custom error message. The following is my sample code snippet.

const userId = Joi.number()
  .integer()
  .required()
  .external(async (value) => {
    let user = await userModel.selectOne({ id: value });
    if (!user) {
      throw new AppError(AppError.INVALID_USER_ID);
    }
  })
  .error(() => { throw new AppError(AppError.INVALID_USER_ID) });

const schema = Joi.object({
      userId
});

schema.validateAsync(userInput);

Expected output:
"message": "Invalid user id."
Actual output:
"message": "Invalid user id." (userId)

It automatically add the field name into my error message. Is there any way to remove it?