We do have two issues here. First of all this should not crash. Digging turned up 361abc55 (cppapi/server/pollthread.cpp: Catch more exceptions, 2020-09-24) which was done for 9.3.5. So you would need to upgrade in order to avoid the crash.
And the second issue is why the forwarding does not work. IIRC you need to start the device with the attributes pointed to first and then the ones with the forwarded attributes.