recorderManager.onFrameRecorded frameBuffer可能为空？

就这么简单的一段代码，日志里记录下每次录制的帧大小：

recorderManager.onFrameRecorded(function(res) {       const {         frameBuffer       } = res       logger.info('[' + recorderId + ']' + 'record.onFrameRecorded: frameBuffer.byteLength=' + frameBuffer.byteLength)     })

但是偶尔会收到这样的异常：

Cannot read property ‘byteLength’ of undefined;at recorderManager.onFrameRecorded callback function TypeError: Cannot read property ‘byteLength’ of undefined

按照官方文档里的说明，这个是录制完指定帧大小的文件后才回调的，按理来讲，不该出现frameBuffer是undefined的情况吧？