Well, what I can suggest is to try and install your template in multiple environments. For example, You may be using MAMP or XAMPP and it would have a certain settings or options activated that might not be available on a production environment.
Try installing it on a demo hosting account, or two different demo hosting accounts. You can also try it on free hosting accounts since they usually lack many php settings.
Also, have you tried Theme Check plugin?
I may not be an expert here, but the above might help you 