Narrow further

app/worker.ts

@@ -119,7 +119,18 @@ export default function start(self: ServiceWorkerGlobalScope) {
       message: `Existing subscription ID ${existingSubscriptionId}`,
     })
 
-    const applicationServerKey = urlB64ToUint8Array(pushPublicKey)
+    await sendMessage({
+      message: `pushPublicKey ${pushPublicKey}`,
+    })
+
+    let applicationServerKey
+    try {
+      applicationServerKey = urlB64ToUint8Array(pushPublicKey)
+    } catch (error) {
+      await sendMessage({
+        message: `B64 error ${(error as Error).toString()}`,
+      })
+    }
 
     await sendMessage({
       message: `Converted public key`,