Sometimes when attempting to decode invalid JSON with the version 3.1 I see this sort of return value:

{:error, :invalid, 0}

The docs seem to indicate that the error tuples should be one of these:

{:error, :invalid}
{:error, {:invalid, String.t}}

I think this line is the culprit:

• https://github.com/devinus/poison/blob/master/lib/poison/parser.ex#L54

I think it was from this PR:

• Begin reporting parser position on failures #100

@devinus would you accept a PR to change the error tuple from this:

{:error, :invalid, 0}

to this?

{:error, {:invalid, 0}}

I would also update the docs to include this as a possible error tuple to indicate the position:

{:error, {:invalid, integer}}