fix: prevent double renders when pushing stacks. (#24147)

# Why

Prevent double renders by cloning state to avoid leaking state between
functions.

- fix expo/router#838 
- fix expo/router#733
- fix expo/router#320
- The issue expo/router#320 has multiple
different things linked, but the original case appears to be fixed.
- possibly also addresses expo/router#847

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# How

- Prevent mutating the input state to avoid invalidating the nested
state.

# Test Plan

- The testing library doesn't seem to support this case. @marklawlor has
been tasked with ensuring the original branch can detect the error
https://github.com/expo/expo/compare/%40evanbacon/router/fix-838
Just in case the testing library isn't fixed, I ran locally with:

- `app/_layout.js`, `app/(a)/_layout.js`, `app/b/_layout.js`
```js
import { Slot } from "expo-router";
export default function RootLayout() {
  return <Slot />
}
```
- `app/(a)/index.js`
```js
import { router, useNavigation } from "expo-router";
import {  View } from "react-native";

export default function App() {
  // const navigation = useNavigation();

  setTimeout(() => {
    router.push("/b");
    // navigation.push("b");
  });
  return (
    <View />
  );
}
```
- `app/b/index.js`
```js
import { usePathname } from 'expo-router';
import { Text, View } from 'react-native';

let i = 0;
export default function Page() {
  const path = usePathname();
  i++;
  return (
    <View style={{ flex: 1, backgroundColor: i > 1 ? "red" : "white" }}>
      <Text>Path: {path}</Text>
    </View>
  );
}
```



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# Checklist

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This is required for changes to Expo modules.
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- [ ] Documentation is up to date to reflect these changes (eg:
https://docs.expo.dev and README.md).
- [ ] Conforms with the [Documentation Writing Style
Guide](https://github.com/expo/expo/blob/main/guides/Expo%20Documentation%20Writing%20Style%20Guide.md)
- [ ] This diff will work correctly for `npx expo prebuild` & EAS Build
(eg: updated a module plugin).

---------

Co-authored-by: Expo Bot <34669131+expo-bot@users.noreply.github.com>

CHANGELOG.md

@@ -12,6 +12,7 @@
 
 ### 🐛 Bug fixes
 
+- Prevent double renders when pushing stacks. ([#24147](https://github.com/expo/expo/pull/24147) by [@EvanBacon](https://github.com/EvanBacon))
 - Patch `react-native-web` AppContainer to prevent adding extra divs. ([#24093](https://github.com/expo/expo/pull/24093) by [@EvanBacon](https://github.com/EvanBacon))
 - Allow pushing "sibling" routes by the same name. ([#23833](https://github.com/expo/expo/pull/23833) by [@EvanBacon](https://github.com/EvanBacon))
 - Prevent throwing in `canGoBack` before the navigation has mounted. ([#23959](https://github.com/expo/expo/pull/23959) by [@EvanBacon](https://github.com/EvanBacon))

src/fork/__tests__/getPathFromState-upstream.test.node.ts

@@ -189,6 +189,58 @@ type State = PartialState<NavigationState>;
   });
 });
 
+it(`does not mutate incomplete state during invocation`, () => {
+  const inputState = {
+    stale: false,
+    type: 'stack',
+    key: 'stack-xxx',
+    index: 1,
+    routeNames: ['(tabs)', 'address'],
+    routes: [
+      {
+        name: '(tabs)',
+        state: {
+          stale: false,
+          type: 'stack',
+          key: 'stack-zzz',
+          index: 0,
+          routeNames: ['index'],
+          routes: [{ name: 'index', path: '', key: 'index-xxx' }],
+        },
+        key: '(tabs)-xxx',
+      },
+      {
+        key: 'address-xxx',
+        name: 'address',
+        params: { initial: true, screen: 'index', path: '/address' },
+      },
+    ],
+  };
+
+  const staticCopy = JSON.parse(JSON.stringify(inputState));
+  getPathFromState(
+    // @ts-expect-error
+    inputState,
+    {
+      screens: {
+        '(tabs)': { path: '(tabs)', screens: { index: '' } },
+        address: {
+          path: 'address',
+          screens: { index: '', other: 'other' },
+          initialRouteName: 'index',
+        },
+        _sitemap: '_sitemap',
+        '[...404]': '*404',
+      },
+      preserveDynamicRoutes: false,
+      preserveGroups: false,
+    }
+  );
+
+  expect(inputState).toEqual(staticCopy);
+  expect(JSON.stringify(inputState)).not.toMatch(/UNKNOWN/);
+});
+
 it(`supports resolving nonexistent, nested synthetic states into paths that cannot be resolved`, () => {
   expect(
     getPathFromState(

src/fork/getPathFromState.ts

@@ -343,7 +343,11 @@ function getPathFromResolvedState(
   while (current) {
     path += '/';
 
-    const route = current.routes[current.index ?? 0] as CustomRoute;
+    // Make mutable copies to ensure we don't leak state outside of the function.
+    const route = {
+      ...(current.routes[current.index ?? 0] as CustomRoute),
+    };
+
     // NOTE(EvanBacon): Fill in current route using state that was passed as params.
     // if (isInvalidParams(route.params)) {
     if (!route.state && isInvalidParams(route.params)) {