fix: handle undefined/null inputs in formatUserMention function

src/utils/userUtils.ts

@@ -33,6 +33,21 @@ export function extractUserFromJid(jid: string): string {
   return normalizeUserIdentifier(phoneNumber);
 }
 
-export function formatUserMention(phoneNumber: string): string {
+export function formatUserMention(phoneNumber?: string): string {
-  return `@${phoneNumber.replace('@', '')}`;
+  if (!phoneNumber) {
+    return '@unknown';
+  }
+  
+  // Handle full JID format
+  if (phoneNumber.includes('@s.whatsapp.net')) {
+    return `@${phoneNumber.split('@')[0]}`;
+  }
+  
+  // Handle already formatted mentions
+  if (phoneNumber.startsWith('@')) {
+    return phoneNumber;
+  }
+  
+  // Handle raw numbers
+  return `@${phoneNumber.replace(/\D/g, '')}`;
 }