Gem::CommandManager#find_command

# File tmp/rubies/ruby-3.2.0/lib/rubygems/command_manager.rb, line 189
def find_command(cmd_name)
  cmd_name = find_alias_command cmd_name

  possibilities = find_command_possibilities cmd_name

  if possibilities.size > 1
    raise Gem::CommandLineError,
          "Ambiguous command #{cmd_name} matches [#{possibilities.join(', ')}]"
  elsif possibilities.empty?
    raise Gem::UnknownCommandError.new(cmd_name)
  end

  self[possibilities.first]
end