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.
let x = props.foo;
                  {
                    let y = props.bar;
                    const fn = useCallback(() => {
                      // nothing
                    }, []);
                  }
                }
              `,
            },
          ],
        },
      ],
    },
    {
      code: normalizeIndent`
        import MutableStore from 'store';
        let z = {};
        function MyComponent(props) {
          let x = props.foo;
          {
            let y = props.bar;
            const fn = useCallback(() => {
              // nothing
            }, [MutableStore?.hello?.world, props.foo, x, y, z, global?.stuff]);
          }
        }
      `,
      errors: [
        {