gateway can not handle incorrect model name

[Jeffwan]

🐛 Describe the bug

If I use a wrong name, it returns some unmarshal error which should be already avoided.

Steps to Reproduce

No response

Expected behavior

No response

Environment

No response

[Jeffwan]

error is from

E1223 19:59:10.389975       1 gateway.go:375] "error to unmarshal response" err="invalid character 'u' looking for beginning of value" requestID="f5f0d4fe-ea19-4137-8367-7fa037d897d3" responseBody="upstream connect error or disconnect/reset before headers. reset reason: protocol error"

If the model is missing, the responseBody is not the right request message upstream connect error or disconnect/reset before headers. reset reason: protocol error

[Jeffwan]

it actually failed at the HandleResponseBody, for such issues, we should block it and return error directly. No need to forward to backend.

[Jeffwan]

We already use Response: &extProcPb.ProcessingResponse_ImmediateResponse to bypass rest process, adding the cache model existing check works as expected