## Describe the bug
I'm trying to configure Free5gc to use CHF from the external provider. I succesfuly registered this CHF in NRF, but when I try to connect UE, the following errors occur (full logs also attached): 

SMF:
2024-04-29T16:59:34.312541475+02:00 [INFO][SMF][PduSess] CHF Selection for SMContext SUPI[imsi-208930000000001] PDUSessionID[2]
2024-04-29T16:59:34.315972245+02:00 [INFO][SMF][Charging] Handle SendConvergedChargingRequest
2024-04-29T16:59:34.316362270+02:00 [ERRO][SMF][GIN] [Debugging] panic:
POST /nsmf-pdusession/v1/sm-contexts HTTP/2.0
(...callstack...)
2024-04-29T16:59:34.316934563+02:00 [INFO][SMF][GIN] | 500 |       127.0.0.1 | POST    | /nsmf-pdusession/v1/sm-contexts |

AMF:
2024-04-29T16:59:34.192410890+02:00 [DEBU][AMF][Gmm][amf_ue_ngap_id:RU:1,AU:1(3GPP)][supi:SUPI:imsi-208930000000001] Search SMF from NRF[http://192.168.16.130:8000]
2024-04-29T16:59:34.256748241+02:00 [ERRO][AMF][Gmm][amf_ue_ngap_id:RU:1,AU:1(3GPP)][supi:SUPI:imsi-208930000000001] CreateSmContextRequest Error: undefined response type

This only happens with an external CHF, when Free5gc CHF is used, everything works ok. 

Except NRF registartion request and watchdog requests I see no other communication between external CHF and Free5gc, so I think the issue is not related to the external CHF response format or behaviour. 

## To Reproduce
1. start Free5gc modules, except of Free5gc-CHF (those are started on VM1: 192.168.16.130)
2. start external CHF (started on VM2: 192.168.16.129). CHF is succesfuly registared in NRF
3. start gNB (UERANSIM on VM2)
4. start UE (UERANSIM on VM2) - this step causes described internal errors on F5gc side.

## Environment (please complete the following information):
 - free5GC Version: v3.4.1
 - OS: Ubuntu Ubuntu 22.04.4 LTS (VM)
 - Kernel version: 6.5.0-28-generic
 - go version: go1.18.1 linux/amd64
 - c compiler version (Option): gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0

## Trace File

### Configuration File
[config_e500.zip](https://github.com/free5gc/free5gc/files/15150191/config_e500.zip)

### PCAP File
[trace.zip](https://github.com/free5gc/free5gc/files/15150219/trace.zip)

### Log File
[amf.log](https://github.com/free5gc/free5gc/files/15150190/amf.log)
[smf.log](https://github.com/free5gc/free5gc/files/15150192/smf.log)

[Bugs] SMF panic on external (3rd party) CHF integration
This is a GitHub Issue
repo:free5gc
owner:free5gc
Title : [Bugs] SMF panic on external (3rd party) CHF integration
Issue date:

--- start body ---
## Describe the bug
I'm trying to configure Free5gc to use CHF from the external provider. I succesfuly registered this CHF in NRF, but when I try to connect UE, the following errors occur (full logs also attached): 

SMF:
2024-04-29T16:59:34.312541475+02:00 [INFO][SMF][PduSess] CHF Selection for SMContext SUPI[imsi-208930000000001] PDUSessionID[2]
2024-04-29T16:59:34.315972245+02:00 [INFO][SMF][Charging] Handle SendConvergedChargingRequest
2024-04-29T16:59:34.316362270+02:00 [ERRO][SMF][GIN] [Debugging] panic:
POST /nsmf-pdusession/v1/sm-contexts HTTP/2.0
(...callstack...)
2024-04-29T16:59:34.316934563+02:00 [INFO][SMF][GIN] | 500 |       127.0.0.1 | POST    | /nsmf-pdusession/v1/sm-contexts |

AMF:
2024-04-29T16:59:34.192410890+02:00 [DEBU][AMF][Gmm][amf_ue_ngap_id:RU:1,AU:1(3GPP)][supi:SUPI:imsi-208930000000001] Search SMF from NRF[http://192.168.16.130:8000]
2024-04-29T16:59:34.256748241+02:00 [ERRO][AMF][Gmm][amf_ue_ngap_id:RU:1,AU:1(3GPP)][supi:SUPI:imsi-208930000000001] CreateSmContextRequest Error: undefined response type

This only happens with an external CHF, when Free5gc CHF is used, everything works ok. 

Except NRF registartion request and watchdog requests I see no other communication between external CHF and Free5gc, so I think the issue is not related to the external CHF response format or behaviour. 

## To Reproduce
1. start Free5gc modules, except of Free5gc-CHF (those are started on VM1: 192.168.16.130)
2. start external CHF (started on VM2: 192.168.16.129). CHF is succesfuly registared in NRF
3. start gNB (UERANSIM on VM2)
4. start UE (UERANSIM on VM2) - this step causes described internal errors on F5gc side.

## Environment (please complete the following information):
 - free5GC Version: v3.4.1
 - OS: Ubuntu Ubuntu 22.04.4 LTS (VM)
 - Kernel version: 6.5.0-28-generic
 - go version: go1.18.1 linux/amd64
 - c compiler version (Option): gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0

## Trace File

### Configuration File
[config_e500.zip](https://github.com/free5gc/free5gc/files/15150191/config_e500.zip)

### PCAP File
[trace.zip](https://github.com/free5gc/free5gc/files/15150219/trace.zip)

### Log File
[amf.log](https://github.com/free5gc/free5gc/files/15150190/amf.log)
[smf.log](https://github.com/free5gc/free5gc/files/15150192/smf.log)

--- end body ---
