Add error log for unsupported types before returning error.

[Chounoki]

No description provided.

[gemini-code-assist]

Code Review

This pull request adds error logging (log.Errorf) before returning gRPC status errors across multiple validation checks and default switch cases in server/service/service.go. The reviewer recommends removing these log statements because logging and returning an error simultaneously leads to duplicate log entries. Additionally, logging client-side input validation failures at the Error level can expose the server to log flooding and potential Denial of Service (DoS) attacks; such logging should instead be handled by top-level callers, gRPC interceptors, or downgraded to a debug level.