Application crashes with Qt5.9.3 and 5.10.0 when unloading a qml loaded with a loader that extend a custom item containing a chart.

Attached is a simple example that reproduces it:
-Run the example and click the red button on top of the window (The button just unload the ChartPage.qml with a source = "")

If in the ChartPage.qml you extend a Rectangle instead of the BasicPage custom item Then it works fine.

The bug are reproducible on windows (tested on 8.1 and 10). linux seems to be working good.