V2: Error does not returns when call GetResponse

[tulzke]

In the comment to the GetResponse method it says:

// GetResponse waits for Future to be filled and returns Response and error.
//
// Note: Response could be equal to nil if ClientError is returned in error.
//
// "error" could be Error, if it is error returned by Tarantool,
// or ClientError, if something bad happens in a client process.
func (fut *Future) GetResponse() (Response, error)

But the actual behavior is different. When an error returns from tarantool, I don't get it.

Here is an example of tarantool configuration:

box.cfg({
    listen = 3301,
    memtx_memory=128 * 1024 * 1024,
    read_only=false,
})

box.once('bootstrap', function()
    box.schema.user.create('test_user', { password = 'test_password' })
    box.schema.user.grant('test_user', 'read,write,execute', 'universe')
end)

api = {}
api.error = function()
    error("test error")
end

And when calling Do with CallRequest, the problem starts. I don't get an error when calling GetResponse from Feature, but only when calling Decode. The behavior differs from the method comment.

func (s *Storage) Call(
	ctx context.Context,
	functionName string,
	args any,
) (tarantool.Response, error) {
	req := tarantool.NewCallRequest(functionName).
		Context(ctx).
		Args(args)

	return s.client.Do(req).GetResponse()
}

// ...

resp, err := storage.Call(ctx, "api.error", []any{})
// test error should return here, but here is nil
if err != nil {
  return err
}

data, err := resp.Decode()
// Actually test error returns here
if err != nil {
  return err
}

[oleg-jukovec]

This is expected behavior, such errors from server cannot be obtained without decoding a response body. But the response body is decoded only inside Response.Get/Response.GetTyped() calls.

It looks like we need to improve the documentation here. Probably we need to add an example of such decoding too.