Programming Ruby 3.2 (5th Edition): B1.0 page 274, Missing in code/gems/aaagmnr


page 274, in Packaging Your RubyGem, paragraph 2, command $ gem build

Missing in code/gems/aaagmnr :

% gem build aaagmnr.gemspec
WARNING:  See for help
ERROR:  While executing gem ... (Gem::InvalidSpecificationException)
    [""] are not files

As I had executed bundle gem aaagmnr on page 266 in another directory, I was able to copy into code/gems/aaagmnr, and could sucessfully build the gem :

% gem build aaagmnr.gemspec
  Successfully built RubyGem
  Name: aaagmnr
  Version: 0.1.0
  File: aaagmnr-0.1.0.gem

The code from the pragprog book site comes without