// would just panic anyway.
		return false
	}
	if types.ConvertibleTo(typ, errorType) {
		return true // via .Error()
	}

	// Does it implement fmt.Stringer?
	if obj, _, _ := types.LookupFieldOrMethod(typ, false, nil, "String"); obj != nil {
		if fn, ok := obj.(*types.Func); ok {
			sig := fn.Type().(*types.Signature)
			if sig.Params().Len() == 0 &&
				sig.Results().Len() == 1 &&