How to include the a field value in another field's error message in Joi

I have a bespoke table editor which is driven by data from the server. it renders a bunch of rows with Name and Quantity fields. All fields are required. The UI shows a validation summary so I'd like to include the value of the Name field in the error message of the associated Quantity field.

e.g.

Please enter a quantity for the 'Beans' field.

My Joi schema is like so:

contaminants: Joi.array().items(
                Joi.object({
                    name: Joi.string(),
                    quantity: Joi.string().
                            .required()
                            .messages({ 'string.base': 'Base error', 'string.empty': 'Empty error' }),
                    })
                })
            ),

How can I use the value of the Name field in the error message of the Quantity field?