Fix unnecessary recreation of react element

Signed-off-by: Philipp Hugenroth <philipph@spotify.com>

packages/core-components/src/layout/Sidebar/Items.tsx

@@ -284,6 +284,8 @@ function isButtonItem(
   return (props as SidebarItemLinkProps).to === undefined;
 }
 
+const sidebarSubmenuType = React.createElement(SidebarSubmenu).type;
+
 // TODO(Rugvip): Remove this once NavLink is updated in react-router-dom.
 //               This is needed because react-router doesn't handle the path comparison
 //               properly yet, matching for example /foobar with /foo.
@@ -490,9 +492,7 @@ export const SidebarItem = forwardRef<any, SidebarItemProps>((props, ref) => {
     // combination with react-hot-loader
     //
     // https://github.com/gaearon/react-hot-loader/issues/304#issuecomment-456569720
-    elements
-      .getElements()
-      .filter(child => child.type === React.createElement(SidebarSubmenu).type),
+    elements.getElements().filter(child => child.type === sidebarSubmenuType),
   );
 
   if (submenu) {

packages/core-components/src/layout/Sidebar/MobileSidebar.tsx

@@ -102,6 +102,8 @@ const sortSidebarGroupsForPriority = (children: React.ReactElement[]) =>
     'desc',
   );
 
+const sidebarGroupType = React.createElement(SidebarGroup).type;
+
 const OverlayMenu = ({
   children,
   label = 'Menu',
@@ -168,9 +170,7 @@ export const MobileSidebar = (props: MobileSidebarProps) => {
   //
   // https://github.com/gaearon/react-hot-loader/issues/304#issuecomment-456569720
   let sidebarGroups = useElementFilter(children, elements =>
-    elements
-      .getElements()
-      .filter(child => child.type === React.createElement(SidebarGroup).type),
+    elements.getElements().filter(child => child.type === sidebarGroupType),
   );
 
   if (!children) {