Imagine you are a librarian managing a library with a unique cataloguing system for books. Each book is assigned a positive integer as its catalogue number. Your task is to find the smallest available catalogue number for a new book.

You have a list of books with the following catalogue numbers: $[1,2,0].$

To add a new book to the library, you need to determine the smallest available catalogue number that is not already assigned. In this case, the answer would be $3$ because it is the smallest positive catalogue number not yet used in your library.

Which of the following Node.js code snippets correctly finds the smallest positive integer not present in the given array nums?