I think this is a bug in your create multi part form: <https://github.com/Uzo2005/nim-openai/blob/main/nim-openai/src/nim_openai/client.nim#L197-L208>
OpenAI api wants everything int its part. See: <https://platform.openai.com/docs/api-reference/images/create-edit> I think you are creating a single entry for the entire json line. But each field in the json needs its own part entry. See my multi part encoder here: <https://github.com/treeform/webby/blob/master/src/webby/multipart.nim>
