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.
useEffect(() => {
                      console.log(local1);
                      console.log(local2);
                    }, [local1, local2]);
                  }
                }
              `,
            },
          ],
        },
      ],
    },
    {
      code: normalizeIndent`
        function MyComponent() {
          const local1 = {};
          const local2 = {};
          useEffect(() => {
            console.log(local1);
            console.log(local2);
          }, [local1]);
        }
      `,
      errors: [
        {
          message:
            "React Hook useEffect has a missing dependency: 'local2'. " +
            'Either include it or remove the dependency array.',
          suggestions: [
            {