[Bug] Error with setting properties of objects created with createObj

I'm trying to create a script that allows players to summon a pet/familiar if they have one. The following script should summon a Furret pokemon familiar into the square of the selected token.

https://gist.github.com/Cazra/8347581

Instead, after some series of deleting and resummoning the familiar (Summon the familiar with the !familiar command, delete it, summon it, then summon it again while it's still out), I get the following error message:

/home/symbly/www/d20-api-server/node_modules/firebase/lib/firebase-node.js:1 orts, require, module, __filename, __dirname) { function f(a){throw a;}var j=v ^ Error: Firebase.child failed: First argument must be a non-empty string and can't contain ".", "#", "$", "[", or "]". at Error () at Ha (/home/symbly/www/d20-api-server/node_modules/firebase/lib/firebase-node.js:12:204) at G.W.H (/home/symbly/www/d20-api-server/node_modules/firebase/lib/firebase-node.js:126:213) at TrackedObj._doSave (

Have I found a bug in the createObj part of the API?

Here: [BUG] trying to update an attribute in a newly created character's journal doesn't work. I was trying to create a journal and then modify an Attribute straight away, and it threw the very same error.
So maybe this is a more "general" error, while I thought it was affecting the journal object only.