Errors, how do they work?

wat_errors.rb

begin
  fail NoMethodError, "foo"
rescue StandardError => e
  puts "NoMethodError is rescued by StandardError: #{e.inspect}"
rescue NoMethodError => e
  puts "NoMethodError is not rescued by StandardError: #{e.inspect}"
  p e
end

puts "NoMethodError is not a StandardError" unless NoMethodError.is_a? StandardError
puts "StandardError is an ancestor of NoMethodError" if NoMethodError.ancestors.include? StandardError
__END__
NoMethodError is rescued by StandardError: #<NoMethodError: foo>
NoMethodError is not a StandardError
StandardError is an ancestor of NoMethodError

Code should have been:

puts "NoMethodError is not a StandardError" unless NoMethodError.new.is_a? StandardError

String is not a String, "string" is a String!