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`
        function MyComponent() {
          const local = {};
          useEffect(debounce(() => {
            console.log(local);
          }, delay), []);
        }
      `,
      errors: [
        {
          message:
            'React Hook useEffect received a function whose dependencies ' +
            'are unknown. Pass an inline function instead.',
          suggestions: [],
        },
      ],
    },
    {
      code: normalizeIndent`
        function MyComponent() {
          const local = {};
          useEffect(() => {
            console.log(local);