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(props) {
          let [, setState] = useState();
          let [, dispatch] = React.useReducer();
          function handleNext1(value) {
            let value2 = value * 100;
            setState(value2);
            console.log('hello');
          }
          const handleNext2 = (value) => {
            setState(foo(value));
            console.log('hello');
          };
          let handleNext3 = function(value) {
            console.log(value);
            dispatch({ type: 'x', value });
          };
          useEffect(() => {
            return Store.subscribe(handleNext1);
          }, []);
          useLayoutEffect(() => {
            return Store.subscribe(handleNext2);
          }, []);
          useMemo(() => {