object_attr_setobj() doesn't return error when used on unsettable attributes

[diablodale]

In the following code

if (MAX_ERR_NONE == object_attr_setobj(myjbox, _sym_object, (t_object *)0x123123llu))
{
    cpost("object value set");
    t_object *objectcheck = jbox_get_object(myjbox);
    cpost("objectcheck=%Ix", objectcheck);
}

The output will be the unexpected

object value set
objectcheck=18180d20     <-- this can vary, the good thing is that it is not 0x123123

Expected is no output at all.
Since the attribute "object" is an unsettable attribute, then an error should be returned causing the if statement to skip output. Instead, object_attr_setobj() silently fails.