diff --git a/src/lib/ae_core/core__export.ts b/src/lib/ae_core/core__export.ts
index 83b99901..eff8717e 100644
--- a/src/lib/ae_core/core__export.ts
+++ b/src/lib/ae_core/core__export.ts
@@ -65,4 +65,4 @@ export async function download_export__obj_type({
     }
 
     return result;
-}
\ No newline at end of file
+}
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index 56d32466..3c555261 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -346,7 +346,9 @@ $effect(() => {
     // Added 2026-06-22 to close this gap.
     // Capture before registering — if null, this is first activation (fresh page load)
     // and the reload is unnecessary since assets were already fetched without the SW.
-    const had_controller = !!navigator.serviceWorker.controller;
+    // Guard must be part of the expression: navigator.serviceWorker doesn't exist on
+    // browsers without SW support, so accessing .controller before checking would throw.
+    const had_controller = 'serviceWorker' in navigator && !!navigator.serviceWorker.controller;
     const on_controller_change = () => {
         if (had_controller) window.location.reload();
     };