So currently this is happening when I set my C language dialect to gnu11. Which one would I have to use for these errors to disappear?

Hey, Ive been trying to run this app from GitHub. It successfully compiled but once it started launching the program only bounced in the dock and didn’t show anything. Here’s what Xcode says Please help me fixing it. I really want to run this app. Many thanks for your help in advance

Hey, I'm not bad with computers but not a developer at all. I really want to use the app from this GitHub page. The problem is that the creator hasn't published a release yet so I have to compile it myself. When I hit build in Xcode it immediately shows a number of errors. How can I fix them and get it to build? Please excuse me very much for asking such a noob question but please help me guys. You would make somebody very happy. Thanks very much for your help in advance!