SSL error on reading https endpoint about just-api HOT 6 CLOSED

node -e 'console.log(process.versions)'

$ curl -v https://api.example.com:8443/graphiql
*   Trying xx.xx.xx.xx...
* TCP_NODELAY set
* Connected to api.example.com (xx.xx.xx.xx) port 8443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
  CAfile: /etc/pki/tls/certs/ca-bundle.crt
  CApath: none
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
* TLSv1.2 (IN), TLS handshake, Server finished (14):
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
* TLSv1.2 (OUT), TLS change cipher, Client hello (1):
* TLSv1.2 (OUT), TLS handshake, Finished (20):
* TLSv1.2 (IN), TLS handshake, Finished (20):
* SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384
* ALPN, server accepted to use h2
* Server certificate:
*  subject: OU=Domain Control Validated; CN=*.example.com
*  start date: Oct 21 19:07:41 2016 GMT
*  expire date: Oct 22 19:07:41 2019 GMT
*  subjectAltName: host "api.example.com" matched cert's "*.example.com"
*  issuer: C=BE; O=GlobalSign nv-sa; CN=SSL CA - SHA256 - G2
*  SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x5651cffe8770)
> GET /graphiql HTTP/2
> Host: api.example.com:8443
> User-Agent: curl/7.59.0
> Accept: */*
> 
* Connection state changed (MAX_CONCURRENT_STREAMS == 128)!
< HTTP/2 200 
< server: nginx
< date: Mon, 02 Jul 2018 04:26:15 GMT
< content-type: text/html;charset=UTF-8
< content-length: 4073
< vary: Accept-Encoding
< vary: Accept-Encoding

$ node -e 'console.log(process.versions)'
{ http_parser: '2.8.0',
  node: '8.11.3',
  v8: '6.2.414.54',
  uv: '1.20.3',
  zlib: '1.2.11',
  ares: '1.10.1-DEV',
  modules: '57',
  nghttp2: '1.32.0',
  napi: '3',
  openssl: '1.1.0h-fips',
  icu: '60.1',
  unicode: '10.0',
  cldr: '32.0',
  tz: '2017c' }