NRF crashes when doing an HTTP2 request when no instance is yet registered

Reported by Andreas Schultz on the mailing list

docker-compose -f docker-compose-basic-nrf.yaml up -d oai-nrf
docker ps -a
CONTAINER ID   IMAGE                                COMMAND                  CREATED         STATUS                    PORTS              NAMES
bf1e0af8b7d2   oaisoftwarealliance/oai-nrf:v1.5.0   "python3 /openair-nr…"   8 minutes ago   Up 18 seconds (healthy)   80/tcp, 9090/tcp   oai-nrf
docker logs -f oai-nrf
[2023-03-09T13:51:26.368928] [nrf] [nrf_app] [info ] ==== OAI-CN5G NRF vBranch: HEAD Abrev. Hash: f66cc2f Date: Wed Jan 18 13:23:43 2023 +0000 ====
[2023-03-09T13:51:26.368955] [nrf] [nrf_app] [info ] Configuration NRF:
[2023-03-09T13:51:26.368960] [nrf] [nrf_app] [info ] - Instance ..............: 0

[2023-03-09T13:51:26.368963] [nrf] [nrf_app] [info ] - PID dir ...............: /var/run

[2023-03-09T13:51:26.368965] [nrf] [nrf_app] [info ] - SBI Interface:
[2023-03-09T13:51:26.368967] [nrf] [nrf_app] [info ]     Interface name ......: eth0
[2023-03-09T13:51:26.368971] [nrf] [nrf_app] [info ]     IPv4 Addr ...........: 192.168.70.130
[2023-03-09T13:51:26.368973] [nrf] [nrf_app] [info ]     Port ................: 80
[2023-03-09T13:51:26.368975] [nrf] [nrf_app] [info ]     HTTP2 port ..........: 8080
[2023-03-09T13:51:26.368978] [nrf] [nrf_app] [info ]     API version..........: v1
[2023-03-09T13:51:26.368984] [nrf] [nrf_app] [start] Starting...
[2023-03-09T13:51:26.369129] [nrf] [nrf_app] [start] Started
[2023-03-09T13:51:26.369939] [nrf] [sbi_srv] [info ] HTTP1 server started
[2023-03-09T13:51:26.370098] [nrf] [nrf_app] [info ] HTTP2 server started

# I first tried in HTTP1 --> OK
curl -s -X GET http://192.168.70.130/nnrf-nfm/v1/nf-instances?nf-type="UPF"

# Then I tried in HTTP2 --> NRF crashes as you described
curl --http2-prior-knowledge -s -X GET http://192.168.70.130:8080/nnrf-nfm/v1/nf-instances?nf-type="UPF"