eslint-plugin-react-hooks version: 4.2.0

## Steps To Reproduce

I know it shouldn't exist in production code, but it's annoying while editing some files.

```js
import React, { useEffect } from "react";

const App = () => {
  useEffect(); // <-
  return null;
};

export default App;
```

Link to code example: https://codesandbox.io/s/polished-sun-3wr27?file=/src/App.js

## The current behavior

ESLint crashed.

```
TypeError: Cannot read property 'type' of undefined
```

## The expected behavior

ESLint doesn't crash but reports an error instead.
if (
              isUsedOutsideOfHook &&
              construction.type === 'Variable' &&
              
              
              
              depType === 'function'
            ) {
              suggest = [
                {
                  desc: `Wrap the ${constructionType} of '${construction.name.name}' in its own ${wrapperHook}() Hook.`,
                  fix(fixer) {
                    const [before, after] =
                      wrapperHook === 'useMemo'
                        ? [`useMemo(() => { return `, '; })']
                        : ['useCallback(', ')'];
                    return [
                      
                      fixer.insertTextBefore(construction.node.init, before),
                      
                      
                      
                      
                      fixer.insertTextAfter(construction.node.init, after),
                    ];
                  },
                },
              ];