From 1b1274f4d35d976b97a2106ccdc6bd45be34f8ca Mon Sep 17 00:00:00 2001
From: hjhopp <33412234+hjhopp@users.noreply.github.com>
Date: Tue, 12 Dec 2023 08:05:52 -0800
Subject: [PATCH] fix: distinguish better between not found and internal error
 (#11131)

Create dedicated NotFound error class for this
---
 .changeset/warm-otters-compete.md          |  5 +++++
 packages/kit/src/runtime/client/client.js  |  7 +++++--
 packages/kit/src/runtime/control.js        | 12 ++++++++++++
 packages/kit/src/runtime/server/respond.js |  4 ++--
 packages/kit/src/runtime/server/utils.js   | 20 ++++++++++----------
 5 files changed, 34 insertions(+), 14 deletions(-)
 create mode 100644 .changeset/warm-otters-compete.md

diff --git a/.changeset/warm-otters-compete.md b/.changeset/warm-otters-compete.md
new file mode 100644
index 000000000000..958a8d40b8a3
--- /dev/null
+++ b/.changeset/warm-otters-compete.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: distinguish better between not-found and internal-error
diff --git a/packages/kit/src/runtime/client/client.js b/packages/kit/src/runtime/client/client.js
index c9216056da92..f64e3447f224 100644
--- a/packages/kit/src/runtime/client/client.js
+++ b/packages/kit/src/runtime/client/client.js
@@ -31,7 +31,7 @@ import * as devalue from 'devalue';
 import { compact } from '../../utils/array.js';
 import { validate_page_exports } from '../../utils/exports.js';
 import { unwrap_promises } from '../../utils/promises.js';
-import { HttpError, Redirect } from '../control.js';
+import { HttpError, Redirect, NotFound } from '../control.js';
 import { INVALIDATED_PARAM, TRAILING_SLASH_PARAM, validate_depends } from '../shared.js';
 import { INDEX_KEY, PRELOAD_PRIORITIES, SCROLL_KEY, SNAPSHOT_KEY } from './constants.js';
 import { stores } from './singletons.js';
@@ -1331,7 +1331,10 @@ export function create_client(app, target) {
 
 		return (
 			app.hooks.handleError({ error, event }) ??
-			/** @type {any} */ ({ message: event.route.id != null ? 'Internal Error' : 'Not Found' })
+			/** @type {any} */ ({
+				message:
+					event.route.id === null && error instanceof NotFound ? 'Not Found' : 'Internal Error'
+			})
 		);
 	}
 
diff --git a/packages/kit/src/runtime/control.js b/packages/kit/src/runtime/control.js
index d27725429038..6bacb73f9273 100644
--- a/packages/kit/src/runtime/control.js
+++ b/packages/kit/src/runtime/control.js
@@ -30,6 +30,18 @@ export class Redirect {
 	}
 }
 
+export class NotFound extends Error {
+	/**
+	 * @param {string} pathname
+	 */
+	constructor(pathname) {
+		super();
+
+		this.status = 404;
+		this.message = `Not found: ${pathname}`;
+	}
+}
+
 /**
  * @template {Record<string, unknown> | undefined} [T=undefined]
  */
diff --git a/packages/kit/src/runtime/server/respond.js b/packages/kit/src/runtime/server/respond.js
index 22fadabf38d3..4e183c53a4f0 100644
--- a/packages/kit/src/runtime/server/respond.js
+++ b/packages/kit/src/runtime/server/respond.js
@@ -18,7 +18,7 @@ import { exec } from '../../utils/routing.js';
 import { redirect_json_response, render_data } from './data/index.js';
 import { add_cookies_to_headers, get_cookies } from './cookie.js';
 import { create_fetch } from './fetch.js';
-import { Redirect } from '../control.js';
+import { Redirect, NotFound } from '../control.js';
 import {
 	validate_layout_exports,
 	validate_layout_server_exports,
@@ -480,7 +480,7 @@ export async function respond(request, options, manifest, state) {
 					manifest,
 					state,
 					status: 404,
-					error: new Error(`Not found: ${event.url.pathname}`),
+					error: new NotFound(event.url.pathname),
 					resolve_opts
 				});
 			}
diff --git a/packages/kit/src/runtime/server/utils.js b/packages/kit/src/runtime/server/utils.js
index 8605076494c6..89cd4e9b8ec5 100644
--- a/packages/kit/src/runtime/server/utils.js
+++ b/packages/kit/src/runtime/server/utils.js
@@ -2,7 +2,7 @@ import { DEV } from 'esm-env';
 import { json, text } from '../../exports/index.js';
 import { coalesce_to_error } from '../../utils/error.js';
 import { negotiate } from '../../utils/http.js';
-import { HttpError } from '../control.js';
+import { HttpError, NotFound } from '../control.js';
 import { fix_stack_trace } from '../shared-server.js';
 import { ENDPOINT_METHODS } from '../../constants.js';
 
@@ -97,17 +97,17 @@ export async function handle_fatal_error(event, options, error) {
 export async function handle_error_and_jsonify(event, options, error) {
 	if (error instanceof HttpError) {
 		return error.body;
-	} else {
-		if (__SVELTEKIT_DEV__ && typeof error == 'object') {
-			fix_stack_trace(error);
-		}
+	}
 
-		return (
-			(await options.hooks.handleError({ error, event })) ?? {
-				message: event.route.id != null ? 'Internal Error' : 'Not Found'
-			}
-		);
+	if (__SVELTEKIT_DEV__ && typeof error == 'object') {
+		fix_stack_trace(error);
 	}
+
+	return (
+		(await options.hooks.handleError({ error, event })) ?? {
+			message: event.route.id === null && error instanceof NotFound ? 'Not Found' : 'Internal Error'
+		}
+	);
 }
 
 /**