Fixed nullpointer in PersonService

src/main/java/ru/nbch/credit_tracker/service/indic/PersonService.java

@@ -88,6 +88,9 @@ public class PersonService {
     }
 
     private PassportData findPassport(List<PassportData> passports) {
+        if (passports == null || passports.isEmpty()) {
+            return null;
+        }
         List<PassportData> documents = passports.stream()
                 .filter(this::isDUL)
                 .toList(); // берем только ДУЛ