QQmlListReference: Calculate element metatype lazily

The calculation is expensive and only needed when inserting elements.
Realize that QQmlMetaType::listType() can never return -1 and remove the
respective early abort conditions. Furthermore, guard against nullptr
element types when inserting. Those would otherwise crash in
canConvert().

Change-Id: Ifaa9d7df1bf8ac372074d25554ec02944d3e3bff
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 5 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmllistreference/data/AListItem.qml b/tests/auto/qml/qqmllistreference/data/AListItem.qml
new file mode 100644
index 0000000000..016d7198f1
--- /dev/null
+++ b/tests/auto/qml/qqmllistreference/data/AListItem.qml
@@ -0,0 +1,5 @@
+import QtQml
+
+QtObject {
+    property int foo: 12
+}