## E0158: unexpected '=>'; expected parameter for arrow function, but got a literal instead

An arrow function has a parameter list followed by `=>` followed by a body. It is a syntax error to write an arrow function with a literal instead of a parameter list:

    let fs = require("fs");
    let path = process.argv[2];
    fs.readFile(path, "utf-8" => {
    });

    const queryUser = userID, groupID = 0 => {
      /* ... */
    };

To fix this error, write a parameter list before `=>`:

    let fs = require("fs");
    let path = process.argv[2];
    fs.readFile(path, "utf-8", (err, data) => {
    });

Alternatively, write `(` `)` around the parameter list:

    const queryUser = (userID, groupID = 0) => {
      /* ... */
    };

Documentation for other errors