Change Hash or Array's `[]` to `fetch` recursively

strict_accessor.rb

# Usage:
# h = StrictAccessor.strictify({a: 1, b: [{c: 3}]})
# h[:c] # KeyError
# h[:b][1] # IndexError
module StrictAccessor
  def self.strictify(object)
    case object
    when Array
      object.map {|e| strictify(e) }.extend(self)
    when Hash
      object.each_with_object({}) {|(k, v), h| h[k] = strictify(v) }.extend(self)
    else
      object
    end
  end

  def [](key_or_index)
    fetch(key_or_index)
  end
end