React components describe an independent and reusable piece of UI. To define it one can declare a function (functional component) or a class (class component). When implementing a class component, a `render` method is required to return the DOM structure, typically with JSX syntax.
When writing the render method in a component it is easy to forget to return the JSX content, which means the component will render nothing. Thus having a `render` method without a single `return` statement is usually a mistake. If it's required that the component renders to nothing, the method should return `null`.
