Provider example crash on close

[KonstantinRitt]

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 ??? 0x000000010dee9f98 qt_meta_stringdata_Qt + 0 1 libqmdnsengine.0.dylib 0x000000010cd2dd3d QMdnsEngine::ProviderPrivate::~ProviderPrivate() + 77 2 libqmdnsengine.0.dylib 0x000000010cd2de7e QMdnsEngine::ProviderPrivate::~ProviderPrivate() + 14 3 org.qt-project.QtCore 0x000000010dba8610 QObjectPrivate::deleteChildren() + 224 4 org.qt-project.QtCore 0x000000010dba83f4 QObject::~QObject() + 1700 5 libqmdnsengine.0.dylib 0x000000010cd2087e QMdnsEngine::Cache::~Cache() + 14 6 org.qt-project.QtCore 0x000000010dba8610 QObjectPrivate::deleteChildren() + 224 7 org.qt-project.QtWidgets 0x000000010cd843f3 QWidget::~QWidget() + 1059 8 provider 0x000000010cd10713 main + 131 9 libdyld.dylib 0x00007fff6ab733d5 start + 1

Qt 5.12.7, OS X 10.14.6