Thanks for being part of the GitHub Community Forum! We're glad you're here.
I wanted to jump in here, and mention that if you don’t get the help you’re looking for from this particular community, you might want to try getting help somewhere that focuses on Thunderbird. It's definitely possible another GitHub user might have run into this same issue and can help, but the GitHub Community Forum focuses primarily on topics related to GitHub, Git, and development projects hosted on GitHub. We want to make sure you're getting the best support you can, but this forum may not be the right place for this particular topic.
Best of luck!
This error only happens with Thunderbird hosted on GitHub.
This is why I did this post here and this is why I wrote that I'm ussing Fedora 28 Atomic Workstation.
Ah, that, of course, makes sense! I just wanted to try and help you find a solution as quickly as possible.
Have you already looked at the Thunderbird repo on GitHub? Most projects allow for issues to ask questions or provide contact information for finding support on their specific projects. It looks like there's a support page for this project on their website. I only mention this because there's no guarantee the project maintainers will see this thread in the forum, and while it's very possible another GitHub user has had this issue and can help here, I want to make sure you have all the possible options for seeking an answer to your question as quickly as possible.