gen_component: unify on_unknown_event and on_exception
gen_component: unify on_unknown_event and on_exception

-> fixes no debug output in unit tests for unknown messages

FS&NK
digshock/scalaris,seyyed/scalaris,seyyed/scalaris,digshock/scalaris,digshock/scalaris,seyyed/scalaris,tectronics/scalaris,digshock/scalaris,seyyed/scalaris,tectronics/scalaris,digshock/scalaris,tectronics/scalaris,seyyed/scalaris,seyyed/scalaris,tectronics/scalaris,tectronics/scalaris,digshock/scalaris,digshock/scalaris,seyyed/scalaris,tectronics/scalaris,tectronics/scalaris