Android: Crashes involving WebView and StackView (Controls 2)

I am posting the following under one report on the (quite possibly naive) assumption these three bugs are linked. If this is wrong then please accept my apologies!

Enclosed in the zip file is an example project. To trigger, simply do the following:

Bug #1
1. Press "Load WebView"
2. Wait until the page has loaded
3. Press the Android 'back' button
4. Repeat points 1-3 once again
EXPECTED: App returns to the screen with the button
ACTUAL: Segmentation fault

Also enclosed is a copy backtrace. I'm not sure how to get GDB to produce more information such as references to source files (is this possible with the current Qt build for Android without recompiling?) but if someone can point me in the right direction then I could perhaps help further.

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Bug #2
1. Press "Load WebView"
2. Immediately hit the back button (before the page has loaded, this has to be fast)
3. Press "Load WebView" again
EXPECTED: App loads the WebView
ACTUAL: Segmentation fault

I haven't obtained a full backtrace on this one, but would note:

 "Thread "QtThread" received signal SIGSEGV, Segmentation fault."
>*stopped,reason="signal-received",signal-name="SIGSEGV",signal-meaning="Segmentation fault",frame={addr="0x00000008",func="??",args=[]},thread-id="13",stopped-threads="all",core="0" 

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To trigger bug #3, first edit 'webview.qml' by replacing "anchors.fill: parent" with the commented lines (these figures are arbitrary). Then:

Bug #3
1. Press "Load WebView"
EXPECTED: WebView page loads
ACTUAL: Segmentation fault

Again, I haven't retrieved a full backtrace on this one, but would note the following:

 >*stopped,reason="signal-received",signal-name="SIGSEGV",signal-meaning="Segmentation fault",frame={addr="0xa136da77",func="QQuickItemPrivate::itemChange(QQuickItem::ItemChange, QQuickItem::ItemChangeData const&)",args=[],from="target:/data/app/org.qtproject.example.bugtest-2/lib/x86/libQt5Quick.so"},thread-id="14",stopped-threads="all",core="1"