Disallow sync function inside async function Using sync functions like `Deno.readTextFileSync` blocks the deno event loop so it's not recommended to use it inside of an async function, because it stops progress of all other async tasks. ### Invalid: ```javascript async function foo() { Deno.readTextFileSync(""); } const fooFn = async function foo() { Deno.readTextFileSync(""); }; const fooFn = async () => { Deno.readTextFileSync(""); }; ``` ### Valid: ```javascript async function foo() { await Deno.readTextFile(""); } function foo() { Deno.readTextFileSync(""); } const fooFn = function foo() { Deno.readTextFileSync(""); }; const fooFn = () => { Deno.readTextFileSync(""); }; ```