web: centralize prop fetching for live + preview, fix preview banner breakage

web/src/app/kontakt/page.tsx

@@ -1,42 +1,19 @@
 import { Metadata, ResolvingMetadata } from "next";
-import { notFound } from "next/navigation";
-import { ContactIndexFragment } from "@/gql/graphql";
-import { getClient } from "@/app/client";
 import {
   ContactIndexView,
-  contactQuery,
+  loadContactIndexProps,
 } from "@/components/contact/ContactIndexView";
 import { getSeoMetadata } from "@/lib/seo";
 
 export async function generateMetadata(
-  { params }: { params: Promise<{}> },
+  _: unknown,
   parent: ResolvingMetadata
 ): Promise<Metadata | null> {
-  const { data, error } = await getClient().query(contactQuery, {});
-
-  if (error) {
-    throw new Error(error.message);
-  }
-  if (!data?.index) {
-    return null;
-  }
-
-  const index = data.index as ContactIndexFragment;
-  const metadata = await getSeoMetadata(index, parent);
-  return metadata;
+  const { index } = await loadContactIndexProps();
+  return getSeoMetadata(index, parent);
 }
 
 export default async function Page() {
-  const { data, error } = await getClient().query(contactQuery, {});
-
-  if (error) {
-    throw new Error(error.message);
-  }
-  if (!data?.index) {
-    return notFound();
-  }
-
-  const index = data.index as ContactIndexFragment;
-
-  return <ContactIndexView index={index} />;
+  const props = await loadContactIndexProps();
+  return <ContactIndexView {...props} />;
 }