Cannot get highlighting to work with new linter

[Andrew de Andrade]

I recently created a new linter, https://github.com/malandrew/syntastic/blob/lint-trap/syntax_checkers/javascript/linttrap.vim which is based on the javascript/eslint.vim linter. 

I didn't really change anything but the bare minimum, but for whatever reason, error highlighting does not work with my linter and I cannot for the life of me figure out why, despite the fact that my linter output format is absolutely identical to eslint.

Here's my syntastic log at loglevel 63:

https://gist.github.com/malandrew/4dff6114d9e3f2ef1540

Any idea what I'm doing wrong?