fix: auto-reload page when stale JS chunks cause blank screen (#63)

After a new deployment, cached HTML pages reference old hashed JS
chunk filenames that no longer exist, resulting in 404s and a blank
page. This adds a client error hook that detects the module import
failure and automatically reloads to fetch fresh assets.

Closes #62

Author: rubenhensen

src/hooks.client.ts

@@ -0,0 +1,10 @@
+import type { HandleClientError } from '@sveltejs/kit'
+
+export const handleError: HandleClientError = ({ error }) => {
+    // When a new deployment happens, old JS chunks are gone.
+    // Detect this and reload the page to get fresh assets.
+    if (error instanceof TypeError && error.message.includes('Importing a module script failed')) {
+        window.location.reload()
+        return
+    }
+}