The "New entry" menu option produces a NoMethodError at the code on line 129:
selected.entries.push(Entry.new(name))
What I'm trying to do here is add the new Entry object to the entries array in the Address_Book object, which is stored in the variable "selected", but I can't see why this code isn't working.
Below is a sample of the program output, and the input I entered at the prompt.
`Address Book
Select an option:
N New address book
S Select address book
E New entry
Q quit
=> n
Making new address book...
Enter your address book name:
=> book1
The currently selected address book is book1
Address Book
Select an option:
N New address book
S Select address book
E New entry
Q quit
=> e
Making new entry...
Enter your new entry name:
=> entry
address-book.rb:129:in <main>': undefined method
entries' for nil:NilClass (NoMethodError)`