add marker in feed to show where they've seen claims, plus other small clean-up

src/views/ContactQRScanShowView.vue

@@ -113,7 +113,10 @@ export default class ContactQRScanShow extends Vue {
     if (!account) {
       this.alertMessage = "You have no identity yet.";
     } else {
-      const identity = JSON.parse(account.identity);
+      const identity = JSON.parse(account?.identity || "null");
+      if (!identity) {
+        throw new Error("No identity found.");
+      }
 
       const publicKeyHex = identity.keys[0].publicKeyHex;
       const publicEncKey = Buffer.from(publicKeyHex, "hex").toString("base64");