I believe this question was more or less answered in another question by
Vladimir Plotvinov. You can view it here:

https://answers.ton.org/question/1538089852979908608/

For sake of visibility, I'll repost his answer:

You recieve a "-13" exit code. API called lite-server and receive some result it's why you got 200 OK. -13 exit code I would say it means method_id not found on smartcontract (but I can't find this remark in documentation).