Inconsistent numbering of shelfs in listing by shelf

[kmnyn]

Error description:
The expected number of shelf is starting from 0 as given by the message when adding a new book. For example: Now you have 1 books on the Shelf: SCIF-0. However when using the listing book by shelf function, the numbering starts from 1.

Steps to reproduce:

1. Add a book in an empty genre, which automatically store on shelf 0.
2. Use list by shelf command
   shelf / scifi / 0
3. Expected:
   Listing out the book on shelf 0.
4. Actual:
   There is no such section!