remove unnecessary patch to readonly state

src/libs/Navigation/AppNavigator/createSplitNavigator/SplitRouter.ts

@@ -31,10 +31,14 @@ function adaptStateIfNecessary({state, options: {sidebarScreen, defaultCentralSc
     const lastRoute = state.routes.at(-1) as NavigationPartialRoute;
     const routePolicyID = getRoutePolicyID(lastRoute);
 
-    // If invalid policy page is displayed on narrow layout, sidebar screen should not be pushed to the navigation state to avoid adding redundant not found page
+    const routes = [...state.routes];
+    let modified = false;
+
+    // If invalid policy page is displayed on narrow layout, sidebar screen should not be
+    // pushed to the navigation state to avoid adding redundant not found page
     if (isNarrowLayout && !!routePolicyID) {
         if (shouldDisplayPolicyNotFoundPage(routePolicyID)) {
-            return;
+            return state; // state is unchanged
         }
     }
 
@@ -52,47 +56,44 @@ function adaptStateIfNecessary({state, options: {sidebarScreen, defaultCentralSc
         // We don't want to get an empty object as params because it breaks some navigation logic when comparing if routes are the same.
         const params = isEmptyObject(copiedParams) ? undefined : copiedParams;
 
-        // @ts-expect-error Updating read only property
-        // eslint-disable-next-line no-param-reassign
-        state.stale = true;
-
-        // @ts-expect-error Updating read only property
-        // Unshift the root screen to fill left pane.
-        state.routes.unshift({
+        routes.unshift({
             name: sidebarScreen,
             // This handles the case where the sidebar should have params included in the central screen e.g. policyID for workspace initial.
             params,
         });
+        modified = true;
     }
 
     // If the screen is wide, there should be at least two screens inside:
     // - sidebarScreen to cover left pane.
     // - defaultCentralScreen to cover central pane.
     if (!isNarrowLayout) {
-        if (state.routes.length === 1 && state.routes[0].name === sidebarScreen) {
+        if (routes.length === 1 && routes.at(0)?.name === sidebarScreen) {
             const previousSameNavigator = rootState?.routes.filter((route) => route.name === parentRoute.name).at(-2);
 
             // If we have optimization for not rendering all split navigators, then last selected option may not be in the state. In this case state has to be read from the preserved state.
             const previousSameNavigatorState = previousSameNavigator?.state ?? (previousSameNavigator?.key ? getPreservedNavigatorState(previousSameNavigator.key) : undefined);
             const previousSelectedCentralScreen =
                 previousSameNavigatorState?.routes && previousSameNavigatorState.routes.length > 1 ? previousSameNavigatorState.routes.at(-1)?.name : undefined;
 
-            // @ts-expect-error Updating read only property
-            // eslint-disable-next-line no-param-reassign
-            state.stale = true;
-
-            // @ts-expect-error Updating read only property
-            // Push the default settings central pane screen.
-            state.routes.push({
+            routes.push({
                 name: previousSelectedCentralScreen ?? defaultCentralScreen,
                 params: state.routes.at(0)?.params,
             });
+            modified = true;
         }
     }
 
-    // @ts-expect-error Updating read only property
-    // eslint-disable-next-line no-param-reassign
-    state.index = state.routes.length - 1;
+    if (!modified) {
+        return state;
+    }
+
+    return {
+        ...state,
+        routes,
+        stale: true,
+        index: routes.length - 1,
+    } as StackState;
 }
 
 function isPushingSidebarOnCentralPane(state: StackState, action: CommonActions.Action | StackActionType, options: SplitNavigatorRouterOptions) {
@@ -101,8 +102,10 @@ function isPushingSidebarOnCentralPane(state: StackState, action: CommonActions.
 
 function SplitRouter(options: SplitNavigatorRouterOptions) {
     const stackRouter = StackRouter(options);
+
     return {
         ...stackRouter,
+
         getStateForAction(state: StackNavigationState<ParamListBase>, action: CommonActions.Action | StackActionType, configOptions: RouterConfigOptions) {
             if (isPushingSidebarOnCentralPane(state, action, options)) {
                 if (getIsNarrowLayout()) {
@@ -114,30 +117,22 @@ function SplitRouter(options: SplitNavigatorRouterOptions) {
             }
             return stackRouter.getStateForAction(state, action, configOptions);
         },
-        getInitialState({routeNames, routeParamList, routeGetIdList}: RouterConfigOptions) {
-            const preservedState = getPreservedNavigatorState(options.parentRoute.key);
-            const initialState = preservedState ?? stackRouter.getInitialState({routeNames, routeParamList, routeGetIdList});
 
-            adaptStateIfNecessary({
-                state: initialState,
-                options,
-            });
+        getInitialState({routeNames, routeParamList, routeGetIdList}: RouterConfigOptions) {
+            const initialState = getPreservedNavigatorState(options.parentRoute.key) ?? stackRouter.getInitialState({routeNames, routeParamList, routeGetIdList});
+            const maybeAdaptedState = adaptStateIfNecessary({state: initialState, options});
 
             // If we needed to modify the state we need to rehydrate it to get keys for new routes.
-            if (initialState.stale) {
-                return stackRouter.getRehydratedState(initialState, {routeNames, routeParamList, routeGetIdList});
+            if (maybeAdaptedState.stale) {
+                return stackRouter.getRehydratedState(maybeAdaptedState, {routeNames, routeParamList, routeGetIdList});
             }
 
-            return initialState;
+            return maybeAdaptedState;
         },
-        getRehydratedState(partialState: StackState, {routeNames, routeParamList, routeGetIdList}: RouterConfigOptions): StackNavigationState<ParamListBase> {
-            adaptStateIfNecessary({
-                state: partialState,
-                options,
-            });
 
-            const state = stackRouter.getRehydratedState(partialState, {routeNames, routeParamList, routeGetIdList});
-            return state;
+        getRehydratedState(partialState: StackState, {routeNames, routeParamList, routeGetIdList}: RouterConfigOptions): StackNavigationState<ParamListBase> {
+            const adaptedState = adaptStateIfNecessary({state: partialState, options});
+            return stackRouter.getRehydratedState(adaptedState, {routeNames, routeParamList, routeGetIdList});
         },
     };
 }