cryptoFramework.Md update 失败报错

private async initDiges() { 
  try { 
    let mMessageDigest = cryptoFramework.createMd("SHA256"); 
    let data = ""; 
    await mMessageDigest.update({ data: this.stringToUint8Array(data) }); 
    let digest = await mMessageDigest.digest() 
  } catch (e) { 
    console.log('createMd error ', e); 
  } 
} 
 
function stringToUint8Array(str: string): Uint8Array { 
  let arr = new Uint8Array(str.length); 
  for (let i = 0, j = str.length; i < j; ++i) { 
    arr[i] = str.charCodeAt(i); 
  } 
  return arr; 
}