fix: add null check in sanitizePhoneNumber helper to prevent errors

src/modules/queue/domain/helpers/time.helper.ts

@@ -15,6 +15,7 @@ export function phoneNumberOnly(phone: string): string {
 }
 
 export function sanitizePhoneNumber(phone: string): string {
+  if (!phone) return phone;
   // Remove all non-numeric characters first
   const cleanPhone = phone.replace(/[^0-9]/g, '');