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.
}
          const handleNext2 = () => {
            console.log('hello');
          };
          let handleNext3 = function() {
            console.log('hello');
          };
          useEffect(() => {
            return Store.subscribe(handleNext1);
          }, [handleNext1]);
          useLayoutEffect(() => {
            return Store.subscribe(handleNext2);
          }, [handleNext2]);
          useMemo(() => {
            return Store.subscribe(handleNext3);
          }, [handleNext3]);
        }
      `,
      errors: [
        {
          message:
            "The 'handleNext1' function makes the dependencies of useEffect Hook " +
            '(at line 14) change on every render. Move it inside the useEffect callback. ' +
            "Alternatively, wrap the definition of 'handleNext1' in its own useCallback() Hook.",
          suggestions: undefined,
        },
        {
          message:
            "The 'handleNext2' function makes the dependencies of useLayoutEffect Hook " +
            '(at line 17) change on every render. Move it inside the useLayoutEffect callback. ' +