rusty_v8 extracting stack trace when a promise rejects

if promise.state() == v8::PromiseState::Rejected {
  let exception = promise.result(scope);
  retval = exception.to_rust_string_lossy(scope);

  if exception.is_native_error() {
   //how to get the exception stack trace to print here?
   // i have retval from above, but it is just the oneliner eg:TypeError: Assignment to constant variable.
   
 }