- 
    Bug 
- 
    Resolution: Out of scope
- 
    P2: Important 
- 
    None
- 
    5.7.0
- 
    None
- 
    Linux, KDE 5, Qt 5.7.0
I am using KDE 5. I can often get tons of this error message from log.
file:///usr/lib/qt5/qml/QtQuick/Controls/Button.qml:100: TypeError: Cannot read property of null file:///usr/lib/qt5/qml/QtQuick/Controls/Button.qml:100: TypeError: Cannot read property of null file:///usr/lib/qt5/qml/QtQuick/Controls/Button.qml:100: TypeError: Cannot read property of null file:///usr/lib/qt5/qml/QtQuick/Controls/Button.qml:100: TypeError: Cannot read property of null
So I find that line:
Button.qml:100
    Binding {
        target: menu
        property: "__minimumWidth"
>      value: button.__panel.width
    }
It seems this line attempted to read width of a null __panel.
I tried to make it be conditional:
    Binding {
        target: menu
        property: "__minimumWidth"
        value: button.__panel ? button.__panel.width: 0
    }
The 'fix' works perfectly, but I don't know whether it will cause other layout crash or not.
Why it was null? Was it normal? Or it was caused by wrong implementations?