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.
'The false literal is not a valid dependency because it never changes. You can safely remove it.',
          suggestions: undefined,
        },
        {
          message:
            'The null literal is not a valid dependency because it never changes. You can safely remove it.',
          suggestions: undefined,
        },
      ],
    },
    {
      code: normalizeIndent`
        function MyComponent() {
          const dependencies = [];
          useEffect(() => {}, dependencies);
        }
      `,
      errors: [
        {
          message:
            'React Hook useEffect was passed a dependency list that is not an ' +
            "array literal. This means we can't statically verify whether you've " +
            'passed the correct dependencies.',
          suggestions: undefined,
        },
      ],
    },
    {
      code: normalizeIndent`
        function MyComponent() {