Hi @Mandrake-ux and welcome on board!
@sethclydesdale is right, GH servers being Linux based have a case-sensitive file system.
Since you didn’t spot the problem locally, I’m assuming you’re working under Windows OS.
With Windows 10 you can now enable case-sensitive behavior on a per-directory basis, which is always a good solution when working with cross-platform projects on GitHub:
I recommend you apply case-sensitiveness to your local GitHub repositories — or store all repositories in a common root folder on which you enable case-sensitiveness — which would allow you to (1) spot case-related issues like this one, (2) prevent cross-platform inadvertent issues, (3) allow you to work with repositories that contain same-named file with different letter casing.
Just be aware that enabling case-sensitive files under Windows might lead to inconsistent behavior with some editors and IDEs, which might not detect correctly name changes or be able to handle same-named files with different casing (you’ll need to test various editors for this).