More silly little mistakes...

main.c

@@ -2755,7 +2755,7 @@ void frame(void)
         printf_buff(&completion_server_url, "%s/completion", SERVER_URL);
         int req_id = EM_ASM_INT({
           return make_generation_request(UTF8ToString($1), UTF8ToString($0));
-          }, completion_server_url, prompt.data);
+          }, completion_server_url.data, prompt.data);
         it->gen_request_id = req_id;
 #endif
 

server/main.go

@@ -256,7 +256,7 @@ func completion(w http.ResponseWriter, req *http.Request) {
 
   if len(splitBody) != 2 {
    w.WriteHeader(http.StatusBadRequest)
-   log.Println("Weird body length %d not 2\n", len(splitBody))
+   log.Printf("Weird body length %d not 2\n", len(splitBody))
    return
   }
   var promptString string = splitBody[1]