[1.16.1] missing == null check in WrittenBookItem.java

[jackokring]

/**

* Gets the generation of the book (how many times it has been cloned)

*/

public static int getGeneration(ItemStack book) {

return book.getTag().getInt("generation");

}

[Draco18s]

1) ItemStacks are never null

2) This method is only ever called on a book that has been written to, which implies that it has NBT data already