Display error as string but not bytes (#7780)

* display error as string but not bytes

* Update routers/repo/http.go

Co-Authored-By: Antoine GIRARD <sapk@users.noreply.github.com>

routers/repo/http.go

@@ -427,7 +427,7 @@ func serviceRPC(h serviceHandler, service string) {
 	cmd.Stdin = reqBody
 	cmd.Stderr = &stderr
 	if err := cmd.Run(); err != nil {
-		log.Error("Fail to serve RPC(%s): %v - %v", service, err, stderr)
+		log.Error("Fail to serve RPC(%s): %v - %s", service, err, stderr.String())
 		return
 	}
 }