Why doesn't the src attribute of the image block work in the project-stub assembly (BEM)?

Question

BEM

Hello!
I started to study the BEM full stack, I do everything according to the instructions .
Added a snippet to index.bemjson.js:

block: 'header',
            content: [
                {
                    block: 'image',
                    attrs: {
                        src: '//varya.me/online-shop-dummy/desktop.blocks/b-logo/b-logo.png'
                    }
            },
                {
                    elem: 'slogan',
                    content: 'A new way of thinking'
                }
            ]

The output is an image block without the src attribute. Moreover, if you use any other attribute (even srcc) it works out with a bang.
What is the reason for this behavior, who knows??
Thanks in advance.