This is a feature request.
Exceptions thrown by the C++ function call itself are
handled by the %exception framework. However,
conversion exceptions from in, out, argout, memberin,
memberout, varin, varout ... typemaps are not caught
by %exception block. While it is possible to handle
each typemap by an individual try/catch block, it
would be nice if there were a similar mechanism, or
if %exception covered conversions as well.