Possibly stupid question, but why does the dog array validate:

  const dogsList = z.array(dogSchema);

  dogSchema.parse([
   { name: 'Cujo', neutered: null },
   { name: 'Fido', age: 4, neutered: true },
  ]); // passes

Since 'Cujo' doesn't have an age? Assuming it's the same dogSchema as in the previous block, age is required, right?

Oh, and a minor typo: This lets you confidently This way you can confidently....