It would be nice if we knew there was a syntax error in the manifest before we even committed it. You can have Puppet check the manifest using the puppet parser validate
command:
vagrant@git:~$ puppet parser validate git.pp Error: Could not parse for environment production: Syntax error at 'require' at /home/vagrant/git.pp:16:3
This is especially useful because a mistake anywhere in the manifest will stop Puppet from running on any node, even on nodes that don't use that particular part of the manifest. So, checking in a bad manifest can cause Puppet to stop applying updates to production for some time, until the problem is discovered, and this could potentially have serious consequences. The best way to avoid this is to automate the syntax check, by using a precommit hook in your version control repo.