looking at the v4 documentation, I see ISSUE, USER, and REPOSITORY as SearchType options, but not CODE. v3 supported code searches via the /search/code endpoint. Is there equivalent functionality in v4 and if so, what does that graph query look like?
No, there currently isn't support for code searches using the GraphQL v4 API. But the API is changing all the time, so you may want to keep an eye on the GraphQL v4 API changelog for updates.
I hope that helps!