OneOf and notOneOf do not handle null and undefined in the error message.

[DaddyWarbucks]

Describe the bug
When using the oneOf or notOneOf with null and undefined the values are not interpolated into the error message properly.

const oneOfSchema = yup.object({
    name: yup
      .string()
      .nullable()
      .oneOf([null, undefined])
  });

// "name must be one of the following values: , "

// ^^ Notice the `null` and `undefined` are not "stringified" into the error message.

To Reproduce

https://codesandbox.io/s/dreamy-elgamal-7d2fv

Expected behavior
When using null or undefined in the oneOf or notOneOf methods the error message will interpolate those values correctly.

Platform (please complete the following information):

• Chrome 79 on macOS (Mojave)
• Version: 0.26.10

Additional context
This may seem silly that someone would mark a schema as nullable but then also set the schema as oneOf([null]), but I have a use case where when using when I believe this makes sense.

stripe_id: yup
      .string()
      .label('Stripe ID')
      .required()
      .nullable()
      .when('type', (type, schema) => {
        // If type is stripe, stripe_id cannot be null and must be provided
        // Otherwise the value must be null
        return type === 'stripe'
          ? schema.nullable(false)
          : schema.oneOf([null]);
      })