I appreciate you taking a look at that. It's strange that you can install it and I can't. But as for the error that you're getting, that seems odd. I only have two is_enabled and the both return either True or False, but I've now forced them to return True until I get this figured out.
Could you have possible installed the wrong package? There is another package with a similar name that hasn't bee updated to ST3 yet. The name of mine is: SfCommand, the name of the other is SymfonyCommander.
Thanks for helping me figure this out!