[Ruby] Exception with a cause :)

exception_with_a_cause.rb

class ExceptionWithACause < StandardError
  attr_reader :cause

  def initialize(message = nil, cause = nil)
    @message = message
    @cause   = cause

    super(message)
  end

  def message
    if @message && @cause
      "#{@message} (cause: [#{@cause.class}] #{@cause.message})"
    elsif @cause
      @cause.message
    elsif @message
      @message
    else
      ""
    end
  end
end

Relevant: https://bugs.ruby-lang.org/issues/8257