How can I add an image using the code editor?

I cannot seem to add an image using the Code Editor of Gutenberg. Using the old WordPress editor, I can click the “Add Media” button, then select the image I want to add and finally click the “Insert into page” button. It’s all very easy.

With Gutenberg this seems impossible if you want to use the Code Editor. The closest I can find is the little + button at the top left. From the menu that pops up you can choose Image, but for some reason it doesn’t add an image. All it does is add this:

<!-- wp:image -->
<figure class="wp-block-image"><img alt=""/></figure>
<!-- /wp:image -->

Does anybody know how you can add an image using the Code Editor? Or has that function been removed?