[shell] Supress warnings/type error for onCountChanged property for undefined lensView.model object - check if model exists before binding to onCountChanged
property. The warnings are:
LensView.qml:48:5: QML Connections: Cannot assign to non-existent property "onCountChanged"
LensView.qml:50: TypeError: Result of expression 'lensView.model' [undefined] is not an object.. Fixes: . Approved by Albert Astals Cid.