webapp-container crashes at exit on desktop

There is a non systematic but consistent crash in the container when it is being closed:

Thread 1 "webapp-containe" received signal SIGSEGV, Segmentation fault.
0x0000000000f52630 in ?? ()
(gdb) bt
#0 0x0000000000f52630 in ?? ()
#1 0x00007ffff6c746c2 in QQmlType::SingletonInstanceInfo::destroy(QQmlEngine*) () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#2 0x00007ffff6c4c220 in QQmlEngine::~QQmlEngine() () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#3 0x00007ffff6c4c349 in QQmlEngine::~QQmlEngine() () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#4 0x0000000000473d60 in BrowserApplication::~BrowserApplication() ()
#5 0x000000000046af28 in WebappContainer::~WebappContainer() ()
#6 0x00000000004671bf in main ()