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.
parser: require.resolve('@typescript-eslint/parser-v2'),
    parserOptions,
  }).run(
    'parser: @typescript-eslint/parser@2.x',
    ReactHooksESLintRule,
    testsTypescriptEslintParser
  );
  new ESLintTester({
    parser: require.resolve('@typescript-eslint/parser-v3'),
    parserOptions,
  }).run(
    'parser: @typescript-eslint/parser@3.x',
    ReactHooksESLintRule,
    testsTypescriptEslintParser
  );
  new ESLintTester({
    parser: require.resolve('@typescript-eslint/parser-v4'),
    parserOptions,
  }).run('parser: @typescript-eslint/parser@4.x', ReactHooksESLintRule, {
    valid: [
      ...testsTypescriptEslintParserV4.valid,
      ...testsTypescriptEslintParser.valid,
    ],
    invalid: [
      ...testsTypescriptEslintParserV4.invalid,
      ...testsTypescriptEslintParser.invalid,
    ],
  });
});