This passage (from another one of the articles on top of HN right now (https://www.wired.com/2015/11/null#tpw)) generates an error when trying to use the Sapien demo: "As a technology journalist, being a Null has served me rather well. (John Dvorak, you know what I’m talking about!) The geek connotations provide a bit of instant nerd cred—to the point where more than one person has accused me of using a nom de plume to make me seem like a bigger nerd than I am.

But there’s a dark side to being a Null, and you coders out there are way ahead of me on this. For those of you unwise in the ways of programming, the problem is that “null” is one of those famously “reserved” text strings in many programming languages. Making matters worse is that software programs frequently use “null” specifically to ensure that a data field is not empty, so it’s often rejected as input in a web form."

Maybe it's the use of the word `Null`? Not sure, but love what you're doing and thought I'd let you know about this.