state timeout exceeded error screen problems on CentOS

[zandbelt]

There are three problems on the error screen when OIDCStateTimeout is exceeded.
I think these are probably bugs, can you comment?

Problems:
The HTTP body part when the OIDCStateTimeout error occurs is duplicated(mod_auth_openidc error page + apache 500 error page), and the Content-length is only the size of the first half of the content.(See Network capture)
The HTTP header shows 200 status, but Apache's access_log shows 500 status, and the 500 error content is added to response.(See access_log and Network capture)
Since the Content-length does not match the actual body size, an error screen may not be displayed correctly when passing through some load balancers (ELB) using IE and Chrome.
My environments:
CentOS 7
Keycloak: 6.0.1
Apache: httpd-2.4.6-90.el7.centos.x86_64
mod_auth version: mod_auth_openidc-2.4.1-1.el7.x86_64
How to reproduce:
Access mod_auth_openidc
Wait at least 30 seconds without logging in to OP
Log in to OP
OIDCStateTimeout error screen appears
Configuration:
<VirtualHost *:80>

ErrorLog "/var/log/httpd/service.example.com/error_log"
TransferLog "/var/log/httpd/service.example.com/access_log"

DocumentRoot /var/www/html

ServerName service.example.com

OIDCResponseType code
OIDCCryptoPassphrase a-random-secret-used-by-apache-oidc-and-balancer
OIDCRemoteUserClaim preferred_username
OIDCProviderMetadataURL https://kc-server.example.com:443/auth/realms/demo/.well-known/openid-configuration

OIDCClientID service
OIDCClientSecret 08e95831-9807-40dd-9d3f-**********
OIDCRedirectURI http://service.example.com/callback

OIDCStateTimeout 30

<Location />
    AuthType openid-connect
    Require valid-user
</Location>

access_log(when OIDCStateTimeout is exceede):
192.178.185.196 - "" [19/Feb/2020:18:06:29 +0900] "GET /callback?state=VYOksbBpcqjPD9pgLUTEEfVWMMQ&session_state=a9522012-ea6b-4db3-b602-4cb89da78025&code=5d9c2f5f-1ba5-4407-8797-721985c7343d.a9522012-ea6b-4db3-b602-4cb89da78025.00b8e388-29bc-4f5e-a736-06b31584a73d HTTP/1.1" 500 1022

Network capture(when OIDCStateTimeout is exceede):