*BLUF*

When my application was bundled with Webpack 1 everything worked
without error. However, when I upgraded to Webpack 4 the rc-tooltip
component used in another package throws a runtime error of

> warning.js:33 Warning: React.createElement: type is invalid
> -- expected a string (for built-in components) or a class/function
> (for composite components) but got: object.

*Dependencies*

```
- ProjectX (my web application)
    - ProjectY (my custom package)
        - rc-tooltip
```

The webpack configuration for ProjectX is shown below.

*Details*

Under both versions, creation of the tooltip appears to be the same.

```
React.createElement(Tooltip, my-props, my-childern):
```

However, inspected what Tooltip actually is under Webpack 1 v Webpack 4
and found a key difference.

Under Webpack 1, on the console

```
> Tooltip
  ƒ Tooltip() {
    var _ref;
    var _temp, _this, _ret;
    (0, _classCallCheck3['default'])(this, Tooltip);
    for (var _len = arguments.length, args = Array(_len), _key = 0; _key < _len; _…
```

Under Webpack 4, on the console

```
> Tooltip
  {default: ƒ, __esModule: true}default: ƒ Tooltip()__esModule: true__proto__: Object
```

It appears that under Webpack 4 I am not receiving the properly
exported class. In fact, on the console I can create a new React
element without error via

```
> React.createElement(Tooltip.default, my-props, my-childern):
```

Why would Webpack 4 alter how a package is expressed in my application?
Is this a configuration issue, what am I missing?