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.
`,
      errors: [
        {
          message:
            "React Hook useEffect has a missing dependency: 'handleNext1'. " +
            'Either include it or remove the dependency array.',
          suggestions: [
            {
              desc: 'Update the dependencies array to be: [handleNext1]',
              output: normalizeIndent`
                function MyComponent(props) {
                  let [, setState] = useState();
                  let [, dispatch] = React.useReducer();
                  let taint = props.foo;
                  // Shouldn't affect anything
                  function handleChange() {}
                  function handleNext1(value) {
                    let value2 = value * taint;
                    setState(value2);
                    console.log('hello');
                  }
                  const handleNext2 = (value) => {
                    setState(taint(value));
                    console.log('hello');
                  };
                  let handleNext3 = function(value) {
                    console.log(taint);
                    dispatch({ type: 'x', value });
                  };
                  useEffect(() => {