If a developer is frequently ignoring returned errors, then they have larger problems and it's their fault. Panic was not added to assist lazy programmers. Even though some API has solidified, an author could later add different return errors. Heck, if that function was calling other functions with returned errors, then the list of possible unique errors increases greatly. You should never ignore an err because you think you know the possible reasons.
The package author should modify the phrasing of that comment.