我正在嘗試學習異步等待。我有下面的代碼，但由于某種原因我得到錯誤"Cannot convert undefined or null to object" on the line:let objArray = Object.entries(dividendFile['Monthly Adjusted Time Series']). 我想這是因為承諾.all在：const apiData = await Promise.all([fetchPrice, fetchDividend])** 不等了嗎？我知道api調用本身并沒有錯，當我單獨嘗試時它工作正常，所以問題是我用異步等待做錯了什么。任何想法可能是什么問題？我認為問題在于：  //API 1    const urlData1 = {         url: 'https://www.alphavantage.co/query?function=',        theFunction: 'TIME_SERIES_DAILY',         symbol: tickerSymbol,         apiKey: key,         outputsize: 'compact'    };        const {url,theFunction,symbol,apiKey, outputsize} = urlData1        const apiUrl1 = `${url}${theFunction}&symbol=${symbol}&outputsize=${outputsize}&apikey=${apiKey}`;        const fetchPrice = fetch(apiUrl1)     //API 2    const urlData2 = {         url2: 'https://www.alphavantage.co/query?function=',        theFunction2: 'TIME_SERIES_MONTHLY_ADJUSTED',         symbol2: tickerSymbol,         apiKey2: key       };      const {url2,theFunction2,symbol2,apiKey2} = urlData2      const apiUrl2 = `${url2}${theFunction2}&symbol=${symbol2}&apikey=${apiKey2}`;      const fetchDividend = fetch(apiUrl2)       const apiData = await Promise.all([fetchPrice, fetchDividend]);  //<--- Seems to be a problem here      const priceFile = await apiData[0].json      const dividendFile = await apiData[1].json  //Get data from API 1  let getPrice = new Promise(resolve => {    let priceArray = Object.entries(priceFile['Time Series (Daily)']) //<--- "Error: Cannot convert undefined or null to object"    let price = parseFloat(priceArray['0']['1']['4. close']);               console.log('price: '+ price)      resolve(price)  })