Do not insert non existing columns
d->sensors is what we derive columnCount() from, when the sensors are changed or the model is reset we called beginInsertColumns for each sensor making the outwards state of the model inconsistent. For example when setting the sensors to a list of 4 sensors, beginInsertColumns would be called 4 times, making some outside observers of the model think it would have 8 columns. So we need to initialize sensorInfos to avoid this. Found when using the model with a QTransposeProxyModel.