Demonstrate opaque errors when sorting objects in Ruby

mets_sort.rb

class Player
  attr_accessor :name, :avg, :hr, :rbi

  def initialize(name, avg, hr, rbi)
    @name = name
    @avg = avg
    @hr = hr
    @rbi = rbi
  end
end

players = [
  Player.new('Dominic Smith', 0.253, 11, 43),
  Player.new('Brandon Nimmo', 0.299, 2, 14),
  Player.new('Michael Conforto', 0.203, 6, 24)
]

puts 'Players before sort'
pp players

# When the data comes in as expected, both `sort` and `sort_by` execute without errors
puts 'Players sorted using sort'
pp players.sort { |first_player, second_player| first_player.avg <=> second_player.avg }
puts 'Players sorted using sort_by'
pp players.sort_by { |player| player.avg }
puts 'Call sort_by to sort by multiple fields'
pp players.sort_by { |player| [player.avg, player.hr] }

# Issues arise when there's missing data
players = [
  Player.new('Dominic Smith', 0.253, 11, 43),
  Player.new('Brandon Nimmo', 0.299, 2, 14),
  Player.new('Michael Conforto', nil, 6, 24)
]

# puts 'Players sorted using sort'
# pp players.sort { |first_player, second_player| first_player.avg <=> second_player.avg }
# Traceback (most recent call last):
# 	1: from mets_sort.rb:37:in `<main>'
# mets_sort.rb:37:in `sort': comparison of Player with Player failed (ArgumentError)

# puts 'Players sorted using sort_by'
# pp players.sort_by { |player| player.avg }
# Traceback (most recent call last):
# 	1: from mets_sort.rb:43:in `<main>'
# mets_sort.rb:43:in `sort_by': comparison of Float with nil failed (ArgumentError)

# puts 'Call sort_by to sort by multiple fields'
# pp players.sort_by { |player| [player.avg, player.hr] }
# Traceback (most recent call last):
# 	1: from mets_sort.rb:49:in `<main>'
# mets_sort.rb:49:in `sort_by': comparison of Array with Array failed (ArgumentError)