Rail's JSON support causes issues

[wagenet]

This can also be produced with the following file:

require "json"

class Exception
  def as_json(options = nil)
    to_s
  end
end

This causes the following backtrace

/Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/utils.rb:4:in `array_update': undefined method `%' for nil:NilClass (NoMethodError)
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/analyzer.rb:234:in `local_update'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/method.rb:117:in `do_check_send'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/method.rb:307:in `block in do_match_iseq_mdef'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/method.rb:306:in `each'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/method.rb:306:in `do_match_iseq_mdef'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/analyzer.rb:2421:in `block in do_define_iseq_method'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/analyzer.rb:2420:in `each'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/analyzer.rb:2420:in `do_define_iseq_method'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/analyzer.rb:1413:in `step'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/analyzer.rb:1050:in `type_profile'
        from /Users/peterwagenet/Development/Ruby/typeprof/lib/typeprof/config.rb:123:in `analyze'
        from exe/typeprof:9:in `<main>'

[wagenet]

So far my best guess is that this happens because this changes the type from what is defined previously via rbs.

[wagenet]

Actually, I believe it's due to the arguments type changing. Another interesting thing to note is that the new return type is ignored.