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 isPropsOnlyUsedInMembers = true;
        for (let i = 0; i < refs.length; i++) {
          const ref = refs[i];
          const id = fastFindReferenceWithParent(
            componentScope.block,
            ref.identifier,
          );
          if (!id) {
            isPropsOnlyUsedInMembers = false;
            break;
          }
          const parent = id.parent;
          if (parent == null) {
            isPropsOnlyUsedInMembers = false;
            break;
          }
          if (
            parent.type !== 'MemberExpression' &&
            parent.type !== 'OptionalMemberExpression'
          ) {
            isPropsOnlyUsedInMembers = false;
            break;
          }
        }
        if (isPropsOnlyUsedInMembers) {
          extraWarning =
            ` However, 'props' will change when *any* prop changes, so the ` +
            `preferred fix is to destructure the 'props' object outside of ` +
            `the ${reactiveHookName} call and refer to those specific props ` +