Compilation from source: LESS file is empty

What is the reason behind the error as below:

Compilation from source: LESS file is empty: frontend/vendor/theme/en_GB/css/style.less

I am using a custom theme that inherits from the default blank theme. This error is getting logged in the exception.log file on every page accessed on the frontend. I even copied the _style.less file from blank theme into the custom theme and ran commands but the error persists.

Note: All the commands run fine without any error but still getting the above-mentioned error in exception.log