"export '...' was not found in '...' " while webpack build

I developed using electron-boilerplate.

I set up environment on my desktop same with my co-worker, node@10.2.0, npm@5.6.0, only difference was OS(co-worker : Windows7 64bit, me: Windows 10 64bit).

However, warning messages outputs follows on runtime.

warning in ./src/pages/config.js

"export 'login' was not found in '../lib/hoeat-api'

The starting point of the program is as follows. npm run build/start.js

Here is the start.js code:

const childProcess = require("child_process");
const electron = require("electron");
const webpack = require("webpack");
const config = require("./webpack.app.config");
const env = "development";
const compiler = webpack(config(env));
let electronStarted = false;

const watching = compiler.watch({}, (err, stats) => {
    if (!err && !stats.hasErrors() && !electronStarted) {
        electronStarted = true;

        childProcess
          .spawn(electron, ["."], { stdio: "inherit" })
          .on("close", () => {
        watching.close();
        });
    }
});

Why does the build using webpack fail?

Thanks for your help. thank you