* @param tag The interned string to search for
* @return The continuation associated with this tag
*/
public Continuation getActiveCatch(Object tag) {
for (int i = catchIndex; i >= 0; i--) {
Continuation c = catchStack[i];
if (c.tag == tag) return c;
}
// if this is a fiber, search prev for tag
ThreadFiber fiber = getFiber();