fix(state): fixing panic when err != nil but response is nil (#2339)

There was a panic when err != nil but response == nil, for example in
the case of: `rpc error: code = NotFound desc = account
celestia1gchva5av4v798xmqttln9qw9smzrjm2cv2q8e7 not found`

```
2023-06-07T14:20:38.731+0200	ERROR	rpc	go-jsonrpc@v0.3.1/handler.go:276	panic in rpc method 'blob.Submit': runtime error: invalid memory address or nil pointer dereference
```

---------

Co-authored-by: Vlad <13818348+walldiss@users.noreply.github.com>

state/core_access.go

@@ -179,7 +179,7 @@ func (ca *CoreAccessor) SubmitPayForBlob(
 		ca.payForBlobCount++
 	}
 
-	if response.Code != 0 {
+	if response != nil && response.Code != 0 {
 		err = errors.Join(err, sdkErrors.ABCIError(response.Codespace, response.Code, response.Logs.String()))
 	}
 	return response, err