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.
{
      code: normalizeIndent`
        const MyComponent = forwardRef((props, ref) => {
          useImperativeHandle(ref, () => ({
            focus() {
              alert(props.hello);
            }
          }), [])
        });
      `,
      errors: [
        {
          message:
            "React Hook useImperativeHandle has a missing dependency: 'props.hello'. " +
            'Either include it or remove the dependency array.',
          suggestions: [
            {
              desc: 'Update the dependencies array to be: [props.hello]',
              output: normalizeIndent`
                const MyComponent = forwardRef((props, ref) => {
                  useImperativeHandle(ref, () => ({
                    focus() {
                      alert(props.hello);
                    }
                  }), [props.hello])
                });
              `,
            },
          ],
        },