当我尝试比较这两种架构时，为什么会变得不确定？

Question

我正在使用dbdiff npm软件包来比较两个数据库的架构。当我插入两个模式时，将得到未定义的输出。 diff.compareSchemas（）也不会让我使用.then语句，可能是因为输出未定义。我不确定我需要做什么才能使输出成为未定义的内容。

const dbdiff = require('dbdiff'),
    diff = new dbdiff.DbDiff(),
    schema = [];

(async () => {
    await dbdiff.describeDatabase({
       dialect: 'mysql', 
       username: 'root',
       password: 'redacted',
       database: 'redacted',
       host: 'localhost',
       dialectOptions: {
          ssl: false
       }
    }).then((res) => {
       schema[0] = res;
    });
   
    await dbdiff.describeDatabase({
       dialect: 'mysql',
       username: 'root',
       password: 'redacted',
       database: 'redacted',
       host: 'localhost',
       dialectOptions: {
          ssl: false
       }
    }).then((res) => {
       schema[1] = res;
    });
    
    const schemaDiff = await diff.compareSchemas(schema[0], schema[1])
    console.log(diff.commands('drop'));
    console.log(schemaDiff);
})();