Fix stacktrace in Module.get_attribute example
Fix stacktrace in Module.get_attribute example

Closes #2522.

kelvinst/elixir,elixir-lang/elixir,kimshrier/elixir,ggcampinho/elixir,lexmag/elixir,joshprice/elixir,pedrosnk/elixir,antipax/elixir,kelvinst/elixir,michalmuskala/elixir,gfvcastro/elixir,kimshrier/elixir,lexmag/elixir,beedub/elixir,antipax/elixir,ggcampinho/elixir,pedrosnk/elixir,gfvcastro/elixir,beedub/elixir