some improvement

app/frontend/src/components/torrent/FileItem.vue

@@ -46,7 +46,7 @@ export default {
     downloadClicked(){
       if(!this.is_download_finished) return;
       if(this.$qt.is_active){
-        this.$qt.callMethod("add_files", this.file);
+        this.$qt.callMethod("add_files", [this.file]);
       }else{
         let a = document.createElement("a");
         a.href = this.file.download_url;