我有一个要拖动的div和一些数据，我对onDrop（）事件上的数据做了很少的修改。div被删除了。 但是，如果我再次拖动同一个div，则会出现以下错误
test.html:57 ERROR TypeError: Converting circular structure to JSON
at JSON.stringify (<anonymous>)
at setDragData (ngx-drag-drop.es5.js:43)
at DndDraggableDirective.push../node_modules/ngx-drag-drop/ngx-drag-drop.es5.js.DndDraggableDirective.onDragStart (ngx-drag-drop.es5.js:320)
at Object.eval [as handleEvent] (test:57)
at handleEvent (core.js:10258)
at callWithDebugContext (core.js:11351)
at Object.debugHandleEvent [as handleEvent] (core.js:11054)
at dispatchEvent (core.js:7717)
at core.js:8161
at HTMLDivElement.<anonymous> (platform-browser.js:995)