improve graphql error handling

web/src/app/lokaler/[slug]/page.tsx

@@ -27,12 +27,15 @@ export async function generateMetadata(
   const { data, error } = await getClient().query(venueBySlugQuery, {
     slug: params.slug,
   });
-  const venue = (data?.venue ?? []) as VenueFragment[];
 
-  if (!venue) {
+  if (error) {
+    throw new Error(error.message);
+  }
+  if (!data?.venue) {
     return null;
   }
 
+  const venue = data.venue as VenueFragment;
   const metadata = await getSeoMetadata(venue, parent);
   return metadata;
 }
@@ -48,11 +51,16 @@ export async function generateStaticParams() {
   `);
   const { data, error } = await getClient().query(allVenueSlugsQuery, {});
 
-  if (data === undefined || error) {
-    throw new Error("failed to generate static params");
+  if (error) {
+    throw new Error(error.message);
+  }
+  if (!data?.pages) {
+    throw new Error(
+      "Failed to generate static params for subpages of /lokaler"
+    );
   }
 
-  return data?.pages.map((page: any) => ({
+  return data.pages.map((page: any) => ({
     slug: page.slug,
   }));
 }
@@ -62,11 +70,14 @@ export default async function Page({ params }: { params: { slug: string } }) {
     slug: params.slug,
   });
 
-  if (data?.venue === null || error) {
+  if (error) {
+    throw new Error(error.message);
+  }
+  if (!data?.venue) {
     return notFound();
   }
 
-  const venue = (data?.venue ?? {}) as VenueFragment;
+  const venue = data.venue as VenueFragment;
   const featuredImage: any = venue.featuredImage;
 
   return (

web/src/app/lokaler/page.tsx

@@ -74,19 +74,30 @@ export async function generateMetadata(
   parent: ResolvingMetadata
 ): Promise<Metadata | null> {
   const { data, error } = await getClient().query(venueIndexQuery, {});
-  const index = (data?.index ?? []) as VenueIndexFragment;
 
-  if (!index) {
+  if (error) {
+    throw new Error(error.message);
+  }
+  if (!data?.index) {
     return null;
   }
 
+  const index = (data?.index ?? []) as VenueIndexFragment;
   const metadata = await getSeoMetadata(index, parent);
   return metadata;
 }
 
 export default async function Page() {
   const { data, error } = await getClient().query(venueIndexQuery, {});
-  const index = (data?.index ?? []) as VenueIndexFragment;
+
+  if (error) {
+    throw new Error(error.message);
+  }
+  if (!data?.index || !data?.venues) {
+    throw new Error("Failed to render /lokaler");
+  }
+
+  const index = data.index as VenueIndexFragment;
   const venues = (data?.venues ?? []) as VenueFragment[];
   const visibleVenues = venues.filter((x) => x.showInOverview);