Issue / code smell in AssociationProxy

I came across an issue in my code and after a hard debug session I found something that smells.

First the context of my issue. I have a AR object that has a polymorphic belongs_to currently tied to nothing, I want to dump it to YAML.     record.to_yaml This raises the following exception:     TypeError: wrong argument type nil (expected Data)       from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/ lib/ruby/1.8/yaml.rb:391:in `emit'       from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/ lib/ruby/1.8/yaml.rb:391:in `quick_emit'       from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/ lib/ruby/1.8/yaml/rubytypes.rb:15:in `to_yaml'

Now to the point: tracing the code path lead me to AssociationProxy#method_missing which for 2.3.x or 3.0.x is very similar:         def method_missing(method, *args)           if load_target             unless @target.respond_to?(method)               message = "undefined method `#{method.to_s}' for \"#{@target}\":#{@target.class.to_s}"               raise NoMethodError, message             end

            if block_given?               @target.send(method, *args) { |*block_args| yield(*block_args) }             else               @target.send(method, *args)             end           end         end

The smell: load_target may return nil, when it does, the return value of method_missing is nil. BUT the caller may have wanted to call a method on nil. Like #to_yaml ! The caller (in this case something in YAML) expects some data back from nil.to_yaml (a string) but it receives nil which later raises the exception.

What about that?