Vuelidate Nesting Question

How do you make a validator for a data structure with a field that has nested fields?

App.vue has a form with a Vuelidate validator. It consists of a name, an address and an optional second Address. Problem is that useVuelidate throws a typescript error on it's second parameter userForm.

Argument of type 'Ref<{ name: string; address: { city: string; street: string; }; secondAddress?: { city: string; street: string; } | undefined; }>' is not assignable to parameter of type '{ name: any; address: any; secondAddress: any; } | Ref<{ name: any; address: any; secondAddress: any; }> | ToRefs<{ name: any; address: any; secondAddress: any; }>'.
  Type 'Ref<{ name: string; address: { city: string; street: string; }; secondAddress?: { city: string; street: string; } | undefined; }>' is not assignable to type 'Ref<{ name: any; address: any; secondAddress: any; }>'.

This happens because the interface UserForm has secondAddress marked as optional.

Question

How do you write the rules in this case, where the field with children is optional?