[Examples] Remove getInitialProps from with-rematch (vercel#13834)

Related to [11014](vercel#11014)

examples/with-rematch/pages/_app.js

@@ -1,17 +1,12 @@
-import App from 'next/app'
 import { Provider } from 'react-redux'
+import { useStore } from '../shared/store'
 
-import withRematch from '../shared/withRematch'
+export default function App({ Component, pageProps }) {
+  const store = useStore(pageProps.initialReduxState)
 
-class MyApp extends App {
-  render() {
-    const { Component, pageProps, reduxStore } = this.props
-    return (
-      <Provider store={reduxStore}>
-        <Component {...pageProps} />
-      </Provider>
-    )
-  }
+  return (
+    <Provider store={store}>
+      <Component {...pageProps} />
+    </Provider>
+  )
 }
-
-export default withRematch(MyApp)

examples/with-rematch/shared/store.js

@@ -1,11 +1,14 @@
+import { useMemo } from 'react'
 import { init } from '@rematch/core'
 import { counter, github } from './models'
 
+let store
+
 const exampleInitialState = {
   counter: 5,
 }
 
-export const initializeStore = (initialState = exampleInitialState) =>
+export const initStore = (initialState = exampleInitialState) =>
   init({
     models: {
       counter,
@@ -15,3 +18,30 @@ export const initializeStore = (initialState = exampleInitialState) =>
       initialState,
     },
   })
+
+export const initializeStore = (preloadedState) => {
+  let _store = store ?? initStore(preloadedState)
+
+  // After navigating to a page with an initial Redux state, merge that state
+  // with the current state in the store, and create a new store
+  if (preloadedState && store) {
+    _store = initStore({
+      ...store.getState(),
+      ...preloadedState,
+    })
+    // Reset the current store
+    store = undefined
+  }
+
+  // For SSG and SSR always create a new store
+  if (typeof window === 'undefined') return _store
+  // Create the store once in the client
+  if (!store) store = _store
+
+  return _store
+}
+
+export function useStore(initialState) {
+  const store = useMemo(() => initializeStore(initialState), [initialState])
+  return store
+}