Bad error message for `to_binary [{}]`

[alco]

to_binary {} gives a proper error message

** (Protocol.UndefinedError) protocol Binary.Chars not implemented for {}

But if we pass it a list that contains non-printable terms, it shows something different:

iex(3)> to_binary [{}]
** (ArgumentError) argument error
    :erlang.iolist_to_binary([{}])
    /Users/alco/Documents/git/elixir/lib/elixir/lib/binary/chars.ex:61: Binary.Chars.List.to_binary/1

[josevalim]

I don't think there is something we can do as checking each item in the
list for validity would be expensive...

José Valim
www.plataformatec.com.br
Skype: jv.ptec
Founder and Lead Developer

[alco]

What about rescuing and reraising with Protocol.UndefinedError?

[josevalim]

@alco that would work, pull request pls? :)