Fixing issue where mobile phone number was not updated, only added if it was not set already

gregui/api/serializers/guest.py

@@ -22,15 +22,14 @@ class GuestRegisterSerializer(serializers.ModelSerializer):
     passport = serializers.CharField(required=False)
 
     def update(self, instance, validated_data):
-        mobile_phone = validated_data.pop("mobile_phone")
-
         if "email" in validated_data:
             email = validated_data.pop("email")
             create_identity_or_update(
                 Identity.IdentityType.PRIVATE_EMAIL, email, instance
             )
 
-        if not instance.private_mobile:
+        if "mobile_phone" in validated_data:
+            mobile_phone = validated_data.pop("mobile_phone")
             create_identity_or_update(
                 Identity.IdentityType.PRIVATE_MOBILE_NUMBER, mobile_phone, instance
             )