disallow async function declarations (es/no-async-functions)
This rule reports ES2017 async functions as errors.
Examples
⛔ Examples of incorrect code for this rule:
/*eslint es/no-async-functions: error */
async function f1() {}
let f2 = async function() {}
let f3 = async () => {}
let obj = { async f4() {} }
class A { async f5() {} }