When failed to get response from ReloadDeclarativeConfig, log "could not unmarshal config error: unexpected end of JSON input" will appear

[randmonkey]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

When failed to get response from ReloadDeclarativeConfig in dbless mode, for example when the client timed out to wait for the response, we will get a nil for response, and try to parse it as a resource parsing error. This causes log

level=error msg="failed parsing resource errors" error="could not unmarshal config error: unexpected end of JSON input" 

which is misleading.

Expected Behavior

When failed to get response from ReloadDeclarativeConfig, we do not see the misleading error could not unmarshal.

Steps To Reproduce

1. Deploy KIC & Kong gateway, and set CONTROLLER_PROXY_TIMEOUT_SECONDS to a short duration (like 1 for 1 second)
2. create many ingresses to generate a configuration with large size
3. When the reloading configuration fails, we will see "could not unmarshal config error: unexpected end of JSON input" in KIC log

Kong Ingress Controller version

v2.11.1

Kubernetes version

No response

Anything else?

No response