Crash under dnf5daemon::DownloadCB::create_signal_download()

[mcrha]

This is with git main at commit 50e84a8. I tried to install a gnucash through the dnf5daemon's session and it crashed with the following backtrace:

Thread 51 "dnf5daemon-serv" received signal SIGSEGV, Segmentation fault.

#0  0x00007ffff413a209 in message_append_basic.lto_priv () at /lib64/libsystemd.so.0
#1  0x00007ffff7f7c153 in sdbus::Message::operator<<(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) () at /lib64/libsdbus-c++.so.1
#2  0x000000000046098d in dnf5daemon::DownloadCB::create_signal_download (this=this@entry=0x7fffe43bdef0, signal_name="download_end", user_data=user_data@entry=0x7fffb8455060)
    at .../dnf5/dnf5daemon-server/callbacks.cpp:52
#3  0x0000000000461564 in dnf5daemon::DownloadCB::end (this=0x7fffe43bdef0, user_cb_data=0x7fffb8455060, status=libdnf5::repo::DownloadCallbacks::TransferStatus::ERROR, msg=0x7ffff6b6706f "Interrupted")
    at .../dnf5/dnf5daemon-server/callbacks.cpp:86
#4  0x00007ffff646f637 in libdnf5::repo::PackageTarget::~PackageTarget (this=0x7fffb8011fa0, __in_chrg=<optimized out>) at .../dnf5/libdnf5/repo/package_downloader.cpp:61
#5  std::destroy_at<libdnf5::repo::PackageTarget> (__location=0x7fffb8011fa0) at /usr/include/c++/14/bits/stl_construct.h:88
#6  std::_Destroy<libdnf5::repo::PackageTarget> (__pointer=0x7fffb8011fa0) at /usr/include/c++/14/bits/stl_construct.h:149
#7  std::_Destroy_aux<false>::__destroy<libdnf5::repo::PackageTarget*> (__first=0x7fffb8011fa0, __last=0x7fffb80128a0) at /usr/include/c++/14/bits/stl_construct.h:163
#8  std::_Destroy<libdnf5::repo::PackageTarget*> (__first=<optimized out>, __last=0x7fffb80128a0) at /usr/include/c++/14/bits/stl_construct.h:196
#9  std::_Destroy<libdnf5::repo::PackageTarget*, libdnf5::repo::PackageTarget> (__first=<optimized out>, __last=0x7fffb80128a0) at /usr/include/c++/14/bits/alloc_traits.h:944
#10 std::vector<libdnf5::repo::PackageTarget, std::allocator<libdnf5::repo::PackageTarget> >::~vector (this=0x7fffb80138b0, __in_chrg=<optimized out>) at /usr/include/c++/14/bits/stl_vector.h:735
#11 libdnf5::repo::PackageDownloader::Impl::~Impl (this=0x7fffb80138a0, __in_chrg=<optimized out>) at .../dnf5/libdnf5/repo/package_downloader.cpp:107
#12 std::default_delete<libdnf5::repo::PackageDownloader::Impl>::operator() (this=0x7fffce9ff6f0, __ptr=0x7fffb80138a0) at /usr/include/c++/14/bits/unique_ptr.h:93
#13 std::default_delete<libdnf5::repo::PackageDownloader::Impl>::operator() (this=0x7fffce9ff6f0, __ptr=0x7fffb80138a0) at /usr/include/c++/14/bits/unique_ptr.h:87
#14 std::unique_ptr<libdnf5::repo::PackageDownloader::Impl, std::default_delete<libdnf5::repo::PackageDownloader::Impl> >::~unique_ptr (this=0x7fffce9ff6f0, __in_chrg=<optimized out>) at /usr/include/c++/14/bits/unique_ptr.h:398
#15 libdnf5::repo::PackageDownloader::~PackageDownloader (this=this@entry=0x7fffce9ff6f0, __in_chrg=<optimized out>) at .../dnf5/libdnf5/repo/package_downloader.cpp:125
#16 0x00000000004238c2 in Session::download_transaction_packages (this=this@entry=0x7fffe4001d80) at /usr/include/c++/14/bits/allocator.h:182
#17 0x00000000004fc2a9 in Goal::do_transaction (this=0x7fffe43aa330, call=...) at .../dnf5/dnf5daemon-server/services/goal/goal.cpp:313
#18 0x000000000051514f in ThreadsManager::handle_method<Goal>(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)::{lambda(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)#1}::operator()(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >) const
    (__closure=__closure@entry=0x8bb758, service=..., method=<optimized out>, call=..., thread_locale=std::optional [no contained value]) at .../dnf5/dnf5daemon-server/./threads_manager.hpp:68
#19 0x000000000051684b in std::__invoke_impl<void, ThreadsManager::handle_method<Goal>(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)::{lambda(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)#1}, std::reference_wrapper<Goal>, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >(std::__invoke_other, ThreadsManager::handle_method<Goal>(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)::{lambda(Goal&, sdbus::MethodReply (Goal::*&&)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)#1}, std::reference_wrapper<Goal>&&, sdbus::MethodReply (Goal::*&&)(sdbus::MethodCall&), sdbus::MethodCall&&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >&&) (__f=...) at /usr/include/c++/14/bits/invoke.h:61
#20 std::__invoke<ThreadsManager::handle_method<Goal>(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)::{lambda(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)#1}, std::reference_wrapper<Goal>, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >(Goal&&, std::reference_wrapper<Goal>&&, sdbus::MethodReply (Goal::*&&)(sdbus::MethodCall&), sdbus::MethodCall&&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >&&) (__fn=...) at /usr/include/c++/14/bits/invoke.h:96
#21 std::thread::_Invoker<std::tuple<ThreadsManager::handle_method<Goal>(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)::{lambda(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)#1}, std::reference_wrapper<Goal>, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >::_M_invoke<0ul, 1ul, 2ul, 3ul, 4ul>(std::_Index_tuple<0ul, 1ul, 2ul, 3ul, 4ul>)
    (this=0x8bb6f8) at /usr/include/c++/14/bits/std_thread.h:301
#22 std::thread::_Invoker<std::tuple<ThreadsManager::handle_method<Goal>(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)::{lambda(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)#1}, std::reference_wrapper<Goal>, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >::operator()() (this=0x8bb6f8) at /usr/include/c++/14/bits/std_thread.h:308
#23 std::thread::_State_impl<std::thread::_Invoker<std::tuple<ThreadsManager::handle_method<Goal>(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)::{lambda(Goal&, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >)#1}, std::reference_wrapper<Goal>, sdbus::MethodReply (Goal::*)(sdbus::MethodCall&), sdbus::MethodCall, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >::_M_run() (this=0x8bb6f0)
    at /usr/include/c++/14/bits/std_thread.h:253
#24 0x00007ffff3ee7564 in execute_native_thread_routine () at /lib64/libstdc++.so.6
#25 0x00007ffff3ca91b7 in start_thread () at /lib64/libc.so.6
#26 0x00007ffff3d2b39c in clone3 () at /lib64/libc.so.6

(gdb) f 2
#2  0x000000000046098d in dnf5daemon::DownloadCB::create_signal_download (this=this@entry=0x7fffe43bdef0, signal_name="download_end", user_data=user_data@entry=0x7fffb8455060)
    at .../dnf5/dnf5daemon-server/callbacks.cpp:52
52	        signal << data->download_id;
(gdb) p data
$1 = (dnf5daemon::DownloadUserData *) 0x7fffb8455060
(gdb) p *data
$2 = {download_id = <error: Cannot access memory at address 0x7ff847becbc5>}
(gdb) l
47	
48	sdbus::Signal DownloadCB::create_signal_download(const std::string & signal_name, void * user_data) {
49	    auto signal = create_signal(dnfdaemon::INTERFACE_BASE, signal_name);
50	    if (user_data) {
51	        auto * data = reinterpret_cast<DownloadUserData *>(user_data);
52	        signal << data->download_id;
53	    }
54	    return signal;
55	}
56