web: reload on chunk load errors after a deploy

web/src/app/error.tsx

@@ -1,8 +1,22 @@
 "use client";
 
+import { useEffect } from "react";
 import { PageHeader } from "@/components/general/PageHeader";
+import { isChunkLoadError } from "@/lib/chunkError";
+
+const RELOAD_KEY = "chunk-error-reload";
+const RELOAD_COOLDOWN_MS = 10_000;
+
+function ErrorPage({ error }: { error: Error & { digest?: string } }) {
+  useEffect(() => {
+    if (!isChunkLoadError(error)) return;
+    // No reload loop if the chunk is gone for good
+    const last = Number(sessionStorage.getItem(RELOAD_KEY) ?? 0);
+    if (Date.now() - last < RELOAD_COOLDOWN_MS) return;
+    sessionStorage.setItem(RELOAD_KEY, String(Date.now()));
+    window.location.reload();
+  }, [error]);
 
-function ErrorPage() {
   return (
     <main className="site-main" id="main">
       <div>

web/src/lib/chunkError.test.ts

@@ -0,0 +1,30 @@
+import { describe, expect, it } from "vitest";
+
+import { isChunkLoadError } from "./chunkError.ts";
+
+describe("isChunkLoadError", () => {
+  it("matches the turbopack chunk loader error", () => {
+    const error = new Error(
+      "Failed to load chunk /_next/static/chunks/0xd_vh2ud8yl-.js from module 64893"
+    );
+    error.name = "ChunkLoadError";
+    expect(isChunkLoadError(error)).toBe(true);
+  });
+
+  it("matches by message when the name is generic", () => {
+    expect(isChunkLoadError(new Error("Loading chunk 123 failed."))).toBe(true);
+    expect(
+      isChunkLoadError(
+        new TypeError("Failed to fetch dynamically imported module: https://neuf.no/x.js")
+      )
+    ).toBe(true);
+    expect(isChunkLoadError(new TypeError("Importing a module script failed."))).toBe(true);
+  });
+
+  it("ignores other errors", () => {
+    expect(isChunkLoadError(new Error("boom"))).toBe(false);
+    expect(
+      isChunkLoadError(new TypeError("Cannot read properties of undefined (reading 'slug')"))
+    ).toBe(false);
+  });
+});

web/src/lib/chunkError.ts

@@ -0,0 +1,9 @@
+// A tab opened before a deploy may reference chunks the new build no longer ships
+export function isChunkLoadError(error: Error): boolean {
+  return (
+    error.name === "ChunkLoadError" ||
+    /failed to load chunk|loading chunk .* failed|dynamically imported module|importing a module script failed/i.test(
+      error.message
+    )
+  );
+}