Expected RGBColor, Counter, Rect behavior

If a user has a reference to an outstanding RGBColor, Counter or Rect
object and the object is removed from its parent CSSStyleDeclaration, are
calls to the outstanding objects expected to throw an exception?

Ex [assuming I have a CSSStyleDeclaration named 'style']

//create property
style.setProperty( "content", " counter(par-num, upper-roman) \". \"  ",
"" ); 

//retrieve counter object
CSSPrimitiveValue pv = (CSSPrimitiveValue)style.getPropertyCSSValue(
"content" );
Counter counter = pv.getCounterValue();

//remove property
style.removeProperty("content");


//use counter interface eventhough it has been removed.
counter.getIdentifier();

Should the last line throw some type of invalid state exception?  Thanks
for the clarification.
----
Blaine