Custom CSS bundle - LESS file is empt (deferred-blog.less) error

[gkopec]

I'm trying to deploy static content locally but keep receiving this error:

Compilation from source: /home/magento/app/design/frontend/Local/breeze-custom/web/css/deferred-blog.less
Compilation from source: LESS file is empty: frontend/Local/breeze-custom/pl_PL/css/deferred-blog.less

Error happened during deploy process: Compilation from source: /home/magento/app/design/frontend/Local/breeze-custom/web/css/deferred-blog.less
Compilation from source: LESS file is empty: frontend/Local/breeze-custom/pl_PL/css/deferred-blog.less

Here is how deferred-blog.less body looks like:

@import 'blog.less';
@critical: false;

and blog.less:

@import (reference) 'abstracts/_all.less';
@import (reference) 'extend/abstracts/_all.less';

@import 'blog/_main.less';
@import 'blog/_list.less';
@import 'blog/_post.less';

@import 'vendor/_luma.less';
@import (reference) 'abstracts/variables/_system.less';

My files structure:

css
├── _extend-checkout.less
├── _extend.less
├── blog
│   ├── _list.less
│   ├── _main.less
│   └── _post.less
├── blog.less
├── deferred-blog.less
└── extend
    ├── abstracts
    │   ├── _all.less
    │   ├── _variables.less
    │   └── variables

[gkopec]

I removed the deferred-blog.less and compile without it. Then I recreated deferred-blog.less and deployment passed.

[gkopec]

It's about empty:

& when not (@critical) {
}

It can not be empty if deferred-blog.less is there.