Crash on opening certain 4.0.0 score

The sample score from #15372 crashes on opening in today's 5.0 (but not in 4.7).
After opening in 4.5.6 and saving, it opens in 5.0 too.

Originally posted by @Jojo-Schmitz in https://github.com/musescore/MuseScore/issues/30424#issuecomment-3914924567

When running in MSVC's debugger:

stack trace:

>	MuseScore5.exe!mu::playback::PlaybackConfiguration::defaultAuxSendValue(unsigned char index, muse::audio::AudioSourceType sourceType, const muse::String & instrumentSoundId) Line 281	C++
 	MuseScore5.exe!mu::playback::PlaybackController::doAddTrack(const mu::engraving::InstrumentTrackId & instrumentTrackId, const std::string & title, const std::function<void __cdecl(void)> & onFinished) Line 1130	C++
 	MuseScore5.exe!mu::playback::PlaybackController::addTrack(const mu::engraving::InstrumentTrackId & instrumentTrackId, const std::function<void __cdecl(void)> & onFinished) Line 1082	C++
 	MuseScore5.exe!mu::playback::PlaybackController::setupSequenceTracks() Line 1450	C++
 	MuseScore5.exe!mu::playback::PlaybackController::setupNewCurrentSequence(const int sequenceId) Line 1357	C++
 	MuseScore5.exe!mu::playback::PlaybackController::init::__l2::<lambda_10>::()::__l2::<lambda_1>::operator()(const int & sequenceId) Line 145	C++
 	[External Code]	
 	MuseScore5.exe!kors::async::Promise<int>::onResolve::__l2::<lambda_1>::operator()(const std::shared_ptr<kors::async::Promise<int>::Data> & d, const int & <args_0>) Line 180	C++
 	[External Code]	
 	MuseScore5.exe!kors::async::ChannelImpl<std::shared_ptr<kors::async::Promise<int>::Data>,int>::ThreadData::receiversCall(const std::shared_ptr<kors::async::Promise<int>::Data> & <args_0>, const int & <args_1>) Line 197	C++
 	MuseScore5.exe!kors::async::ChannelImpl<std::shared_ptr<kors::async::Promise<int>::Data>,int>::sendAuto(const std::shared_ptr<kors::async::Promise<int>::Data> & <args_0>, const int & <args_1>) Line 414	C++
 	MuseScore5.exe!kors::async::ChannelImpl<std::shared_ptr<kors::async::Promise<int>::Data>,int>::send(kors::async::SendMode mode, const std::shared_ptr<kors::async::Promise<int>::Data> & <args_0>, const int & <args_1>) Line 520	C++
 	MuseScore5.exe!kors::async::Promise<int>::resolve(const int & <args_0>) Line 214	C++
 	MuseScore5.exe!kors::async::Promise<int>::Resolve::operator()(const int & <val_0>) Line 59	C++
 	MuseScore5.exe!muse::audio::Playback::addSequence::__l2::<lambda_1>::()::__l2::<lambda_1>::()::__l2::<lambda_1>::operator()(const muse::audio::rpc::Msg & res) Line 136	C++
 	[External Code]	
 	MuseScore5.exe!muse::audio::rpc::GeneralRpcChannel::receive(muse::audio::rpc::GeneralRpcChannel::RpcData & to, const muse::audio::rpc::Msg & m) Line 128	C++
 	MuseScore5.exe!muse::audio::rpc::GeneralRpcChannel::setupOnMain::__l2::<lambda_1>::operator()(const muse::audio::rpc::Msg & m) Line 52	C++
 	[External Code]	
 	MuseScore5.exe!kors::queue::RpcPort<muse::audio::rpc::Msg>::process() Line 102	C++
 	MuseScore5.exe!muse::audio::rpc::GeneralRpcChannel::process() Line 66	C++
 	MuseScore5.exe!muse::audio::AudioModule::onInit::__l2::<lambda_1>::operator()() Line 106	C++
 	[External Code]	
 	MuseScore5.exe!muse::TickerProvider::process() Line 96	C++
 	MuseScore5.exe!muse::TickerProvider::start::__l2::<lambda_1>::operator()() Line 46	C++
 	MuseScore5.exe!QtPrivate::FunctorCall<std::integer_sequence<unsigned __int64>,QtPrivate::List<>,void,`muse::TickerProvider::start'::`2'::<lambda_1>>::call::__l2::<lambda_1>::operator()() Line 116	C++
 	MuseScore5.exe!QtPrivate::FunctorCallBase::call_internal<void,`QtPrivate::FunctorCall<std::integer_sequence<unsigned __int64>,QtPrivate::List<>,void,`muse::TickerProvider::start'::`2'::<lambda_1>>::call'::`2'::<lambda_1>>(void * * args, QtPrivate::FunctorCall<std::integer_sequence<unsigned __int64>,QtPrivate::List<>,void,`muse::TickerProvider::start'::`2'::<lambda_1>>::call::__l2::<lambda_1> && fn) Line 65	C++
 	MuseScore5.exe!QtPrivate::FunctorCall<std::integer_sequence<unsigned __int64>,QtPrivate::List<>,void,`muse::TickerProvider::start'::`2'::<lambda_1>>::call(muse::TickerProvider::start::__l2::<lambda_1> & f, void * * arg) Line 115	C++
 	MuseScore5.exe!QtPrivate::FunctorCallable<`muse::TickerProvider::start'::`2'::<lambda_1>>::call<QtPrivate::List<>,void>(muse::TickerProvider::start::__l2::<lambda_1> & f, void * __formal, void * * arg) Line 337	C++
 	MuseScore5.exe!QtPrivate::QCallableObject<`muse::TickerProvider::start'::`2'::<lambda_1>,QtPrivate::List<>,void>::impl(int which, QtPrivate::QSlotObjectBase * this_, QObject * r, void * * a, bool * ret) Line 547	C++
 	[External Code]	
 	MuseScore5.exe!main(int argc, char * * argv) Line 173	C++
 	[External Code]