WordPress editor custom styles

Using the following code I’m trying to add some CSS to the default Gutenberg editor in WordPress:

function editor_style() {
    add_theme_support( 'editor-styles' );
    add_editor_style( 'editor-style.css' );
}
add_action( 'after_setup_theme', 'editor_style' );

While this works, it also makes the editor look weird:

enter image description here

It seems as if all styles are removed other than those from my custom stylesheet. Is this intentional? I’m using Bootstrap in my theme. Should I include this here too?