I can see the issue is that the current working directory for the binary is not set correctly. It should be set to the repo root (the folder that contains README.md). The ./bin/gocode/gocode file should be present.
How are you running it? You should open the Xcode project and Run it (Cmd+R). The Xcode project is configured to set the current working directory as the project root folder.
EDIT: Still getting this error though from within the running application: libc++abi.dylib: terminate called without an active exception ls: ./GenProgram: No such file or directory
I've pushed a small update [1] that prints the current working dir of the app. Perhaps you can try it and verify that it's being set correctly. See this screenshot [2] for Xcode setting that sets the running app cwd.
[1] https://github.com/shurcooL/Conception/commit/37bbbb57e56caa...