fix(SW-236): properly handle expired token in webviews

Trying out a new pattern for errors in data fetching.

Next.js is not a fan of throwing errors. Instead it recommends returning
different shapes for each state. Ref:
https://nextjs.org/docs/app/building-your-application/routing/error-handling#handling-expected-errors-from-server-components

It requires some more detailing and a bit more refactoring in non webview part,
but it is a start. This webview specific implementation should not break web.

app/[lang]/webview/[contentType]/[uid]/page.tsx

@@ -1,4 +1,6 @@
-import { notFound } from "next/navigation"
+import { notFound, redirect } from "next/navigation"
+
+import { serverClient } from "@/lib/trpc/server"
 
 import AccountPage from "@/components/ContentType/Webviews/AccountPage"
 import LoyaltyPage from "@/components/ContentType/Webviews/LoyaltyPage"
@@ -13,6 +15,21 @@ import {
 export default async function ContentTypePage({
   params,
 }: PageArgs<LangParams & ContentTypeWebviewParams & UIDParams, {}>) {
+  const user = await serverClient().user.get()
+
+  if (!user) {
+    return <p>Error: No user could be loaded</p>
+  }
+
+  if ("error" in user) {
+    switch (user.cause) {
+      case "unauthorized": // fall through
+      case "forbidden": // fall through
+      case "token_expired":
+        redirect(`/${params.lang}/webview/refresh`)
+    }
+  }
+
   switch (params.contentType) {
     case "loyalty-page":
       return <LoyaltyPage lang={params.lang} />