GitLab

* add warning if font is not set

* added quotes

* added changes after review

* Apply suggestions from code review
Co-authored-by: Philip Meier <github.pmeier@posteo.de>

* escaped warning string

* Apply suggestions from code review
Co-authored-by: Philip Meier <github.pmeier@posteo.de>

* updated warning message in test

* refactored code

* Apply suggestions from code review
Co-authored-by: Philip Meier <github.pmeier@posteo.de>
Co-authored-by: Philip Meier <github.pmeier@posteo.de>
Co-authored-by: Vasilis Vryniotis <datumbox@users.noreply.github.com>