I think what you'd need is an ExprEditor for athrow
bytecodes. If done at that level, the exception object
will already have been constructed, but not yet thrown.
Presumably you could modify or replace it, or do
something else. But you'd need either to return from
the method or throw something that it either handles
locally or that is legal to throw from the method.
Easiest and safest might be to restrict it either to return
(a type-safe value) or throw an object of the original