Stop logging errors on 404

src/hooks.server.ts

@@ -1,5 +1,6 @@
 import { building } from "$app/environment";
 import { resolveConfiguration } from "$lib/server/configuration";
+import type { HandleServerError } from "@sveltejs/kit";
 
 if (!building) {
   // Resolve the configuration on startup, such that startup fails if the
@@ -13,5 +14,10 @@ if (!building) {
 // TODO we should have prom metrics, on, among other things, HTTP requests
 // handled, and the `handle` hook would be a good way to do that.
 
-// TODO SvelteKit logs an error every time anything requests a URL that does not
-// map to a route. Bonkers. Silence those by implementing `handleError`.
+// SvelteKit logs an error every time anything requests a URL that does not map
+// to a route. Bonkers. Override the default behavior to exclude such cases.
+export const handleError: HandleServerError = ({ error, event }) => {
+  if (event.route.id !== null) {
+    console.error(error);
+  }
+};