commit 21e9403c5ce8da4ae2b445d6b9d9d1f2d478d11b
Author: Fabian Kosmale <fabian.kosmale@qt.io>
Date:   Mon Feb 17 13:56:54 2020 +0100

    workaround

diff --git src/qml/qml/qqmlvmemetaobject.cpp src/qml/qml/qqmlvmemetaobject.cpp
index de23e929e2..b8b43d46c4 100644
--- src/qml/qml/qqmlvmemetaobject.cpp
+++ src/qml/qml/qqmlvmemetaobject.cpp
@@ -82,10 +82,12 @@ public:
             return;
         }

-        if (auto *md = static_cast<QV4::MemberData *>(
-                    m_metaObject->propertyAndMethodStorage.asManaged())) {
-            const auto *v = (md->data() + m_id)->as<QV4::VariantObject>();
-            Q_ASSERT(v);
+        if (auto *md = m_metaObject->propertyAndMethodStorageAsMemberData()) {
+            if (md->d()->values.alloc <= m_id)
+                return;
+            const auto *v = md->d()->values[m_id].as<QV4::VariantObject>();//(md->data() + m_id)->as<QV4::VariantObject>();
+            if (!v)
+                return;
             Q_ASSERT(v->d());
             QVariant &data = v->d()->data();
             Q_ASSERT(data.userType() == qMetaTypeId<QVector<QQmlGuard<QObject>>>());
@@ -115,23 +117,33 @@ private:
 static void list_append(QQmlListProperty<QObject> *prop, QObject *o)
 {
     const ResolvedList resolved(prop);
+    if (!resolved.list())
+        return;
     resolved.list()->append(o);
     resolved.activateSignal();
 }

 static int list_count(QQmlListProperty<QObject> *prop)
 {
-    return ResolvedList(prop).list()->count();
+    auto list = ResolvedList(prop).list();
+    if (!list)
+        return 0;
+    return list->count();
 }

 static QObject *list_at(QQmlListProperty<QObject> *prop, int index)
 {
-    return ResolvedList(prop).list()->at(index);
+    auto list = ResolvedList(prop).list();
+    if (!list)
+        return nullptr;
+    return list->at(index);
 }

 static void list_clear(QQmlListProperty<QObject> *prop)
 {
     const ResolvedList resolved(prop);
+    if (!resolved.list())
+        return;
     resolved.list()->clear();
     resolved.activateSignal();
 }
@@ -139,6 +151,8 @@ static void list_clear(QQmlListProperty<QObject> *prop)
 static void list_replace(QQmlListProperty<QObject> *prop, int index, QObject *o)
 {
     const ResolvedList resolved(prop);
+    if (!resolved.list())
+        return;
     resolved.list()->replace(index, o);
     resolved.activateSignal();
 }
@@ -146,6 +160,8 @@ static void list_replace(QQmlListProperty<QObject> *prop, int index, QObject *o)
 static void list_removeLast(QQmlListProperty<QObject> *prop)
 {
     const ResolvedList resolved(prop);
+    if (!resolved.list())
+        return;
     resolved.list()->removeLast();
     resolved.activateSignal();
 }