#vulnerable code 
                                protected void load(boolean strict) {
        try {
            activator = DOMHelper.getElementByAttribute("data-activates", getId());
            getNavMenu().setShowOn(ShowOn.SHOW_ON_MED_DOWN);
            if (alwaysShowActivator && !getTypeMixin().getStyle().equals(SideNavType.FIXED.getCssName())) {
                getNavMenu().setShowOn(ShowOn.SHOW_ON_LARGE);
            } else {
                getNavMenu().setHideOn(HideOn.HIDE_ON_LARGE);
            }
            getNavMenu().removeStyleName(CssName.NAVMENU_PERMANENT);
        } catch (Exception ex) {
            if (strict) {
                throw new IllegalArgumentException(
                        "Could not setup MaterialSideNav please ensure you have " +
                                "MaterialNavBar with an activator setup to match this widgets id.", ex);
            }
        }

        setup();
        setupDefaultOverlayStyle();

        JsSideNavOptions options = new JsSideNavOptions();
        options.menuWidth = width;
        options.edge = edge != null ? edge.getCssName() : null;
        options.closeOnClick = closeOnClick;

        JsMaterialElement element = $(activator);
        element.sideNav(options);

        element.off(SideNavEvents.SIDE_NAV_CLOSING);
        element.on(SideNavEvents.SIDE_NAV_CLOSING, e1 -> {
            onClosing();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_CLOSED);
        element.on(SideNavEvents.SIDE_NAV_CLOSED, e1 -> {
            onClosed();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_OPENING);
        element.on(SideNavEvents.SIDE_NAV_OPENING, e1 -> {
            onOpening();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_OPENED);
        element.on(SideNavEvents.SIDE_NAV_OPENED, e1 -> {
            onOpened();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_OVERLAY_ATTACHED);
        element.on(SideNavEvents.SIDE_NAV_OVERLAY_ATTACHED, e1 -> {
            onOverlayAttached();
            return true;
        });

        $(".collapsible-header").on("click", (e, param1) -> {
            //e.stopPropagation();

            return true;
        });
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                protected void load(boolean strict) {
        try {
            activator = DOMHelper.getElementByAttribute("data-activates", getId());

            MaterialWidget navMenu = getNavMenu();
            if (navMenu != null) {
                navMenu.setShowOn(ShowOn.SHOW_ON_MED_DOWN);
                if (alwaysShowActivator && !getTypeMixin().getStyle().equals(SideNavType.FIXED.getCssName())) {
                    navMenu.setShowOn(ShowOn.SHOW_ON_LARGE);
                } else {
                    navMenu.setHideOn(HideOn.HIDE_ON_LARGE);
                }
                navMenu.removeStyleName(CssName.NAVMENU_PERMANENT);
            }
        } catch (Exception ex) {
            if (strict) {
                throw new IllegalArgumentException(
                        "Could not setup MaterialSideNav please ensure you have " +
                                "MaterialNavBar with an activator setup to match this widgets id.", ex);
            }
        }

        setup();
        setupDefaultOverlayStyle();

        JsSideNavOptions options = new JsSideNavOptions();
        options.menuWidth = width;
        options.edge = edge != null ? edge.getCssName() : null;
        options.closeOnClick = closeOnClick;

        JsMaterialElement element = $(activator);
        element.sideNav(options);

        element.off(SideNavEvents.SIDE_NAV_CLOSING);
        element.on(SideNavEvents.SIDE_NAV_CLOSING, e1 -> {
            onClosing();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_CLOSED);
        element.on(SideNavEvents.SIDE_NAV_CLOSED, e1 -> {
            onClosed();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_OPENING);
        element.on(SideNavEvents.SIDE_NAV_OPENING, e1 -> {
            onOpening();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_OPENED);
        element.on(SideNavEvents.SIDE_NAV_OPENED, e1 -> {
            onOpened();
            return true;
        });

        element.off(SideNavEvents.SIDE_NAV_OVERLAY_ATTACHED);
        element.on(SideNavEvents.SIDE_NAV_OVERLAY_ATTACHED, e1 -> {
            onOverlayAttached();
            return true;
        });

        $(".collapsible-header").on("click", (e, param1) -> {
            //e.stopPropagation();

            return true;
        });
    }