nginx crashes when parsing the nginx config for the stream module

Reproducible: Always

Steps to Reproduce:
1. dnf install nginx-1.28.0-3.fc43.x86_64 nginx-mod-stream-1.28.0-3.fc43.x86_64
2. Create config
cat >tmp.conf <<END
load_module "/usr/lib64/nginx/modules/ngx_stream_module.so";
stream {
  server {
    listen 8080 ssl;
    ssl_certificate /dev/null;
    ssl_certificate_key /dev/null;
  }
}
END
3. nginx -t -e /dev/null -c tmp.conf
4. Expect error parsing certificate (/dev/null is not a valid certificate)
Actual Results:
Crashes with a segfault

Expected Results:
Parse config successfully