In order to submit my very, very basic Mac App to the App Store (very basic since it only contains a single HTML and Javascript file - very simple word game that does NOT require any kind of permissions from the system), Apple requires you to sandbox the app.
The application works completely fine until I codesign it with the most basic Entitlements.plist file as follows:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<!-- Activates the sandbox, required. -->
<key>com.apple.security.app-sandbox</key>
<true/>
</dict>
</plist>
However after codesigning with this, the application crashes upon launch. For what it is worth, the application was built with the submit-to-appstore flag.