anchor.diff:    /// [NavigationRail.labelType] is [NavigationRailLabelType.none], the label is
     /// still used for semantics, and may still be used if
     /// [NavigationRail.extended] is true.
  -  final Widget? label;
  +  final Widget label;
   
     /// The amount of space to inset the destination item.
     final EdgeInsetsGeometry? padding;
  
positive.code:                           extendedTransitionAnimation: _extendedAnimation,
                            selected: widget.selectedIndex == i,
                            icon: widget.selectedIndex == i ? widget.destinations[i].selectedIcon : widget.destinations[i].icon,
                            label: widget.destinations[i].label!,
                            destinationAnimation: _destinationAnimations[i],
                            labelType: labelType,
                            iconTheme: widget.selectedIndex == i ? selectedIconTheme : unselectedIconTheme,
  
negative.code:   const NavigationRailDestination({
      required this.icon,
      Widget? selectedIcon,
      required this.label,
      this.padding,
    }) : selectedIcon = selectedIcon ?? icon,
         assert(icon != null),
         assert(label != null);
  
    /// The icon of the destination.
    ///
  