We should be referring to ParseError.Err, which is the underlying error,
not ParseError.Error, which is the error method.

Change-Id: Ic3cef5ecbe1ada5fa14b9573222f29da8fc9a8d5
Reviewed-on: https://go-review.googlesource.com/72450Reviewed-by: Tim Cooper <tim.cooper@layeh.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>