fix: improve 404 error

index.ts

@@ -27,11 +27,12 @@ app.get("/*", (req: Request, res: Response) => {
   req.log.info(`Request for ${uri}`);
   res.format({
     "text/html": async () => {
-      try {
-        const data = await handleQueryHtml(uri, config.sparqlQueryUrl);
+      const data = await handleQueryHtml(uri, config.sparqlQueryUrl);
+      if (data.outcomingQuads.length === 0 && data.incomingQuads.length === 0) {
+        const message = `<h1>Not Found</h1> <p>There is no data for <a href="${uri}">${uri}</a></p> <p> Endpoint: <a href="${config.sparqlQueryUrl}">${config.sparqlQueryUrl}</a></p>`;
+        return res.status(404).send(message);
+      } else {
         return res.render("results", data);
-      } catch (error) {
-        return res.status(404).send("Not Found");
       }
     },
     "application/n-quads": async () => {

src/renderHtml.ts

@@ -4,10 +4,10 @@ import { toPrefix } from "./utils";
 const handleQueryHtml = async (uri: string, endpoint: string) => {
   const outcomingQuads = await performQueryHtml(uri, endpoint);
   const incomingQuads = await performIncomingQueryHtml(uri, endpoint);
-  if (outcomingQuads.length === 0 && incomingQuads.length === 0) {
-    throw new Error("Not Found");
-  }
-  const title = getTitle();
+  const title =
+    outcomingQuads.length === 0 && incomingQuads.length === 0
+      ? "Not Found"
+      : getTitle();
   return {
     incomingQuads: incomingQuads,
     outcomingQuads: outcomingQuads,

src/types.ts

@@ -1,3 +1,5 @@
+import type * as RDF from "@rdfjs/types";
+
 interface Config {
   sparqlQueryUrl: string;
   port: number;
@@ -10,4 +12,9 @@ interface Prefix {
   uri: string;
 }
 
-export { Config, Prefix };
+interface QueryResults {
+  quads: RDF.Quad[];
+  query: string;
+}
+
+export { Config, Prefix, QueryResults };