fillForm doesn't create a new PDF when running on Heroku

[aphavichitr]

I'm unable to generate a new PDF when running on Heroku. This works fine when I'm running locally. I've added the buildpack https://github.com/shake-apps/heroku-buildpack-pdftk.git through the heroku dashboard settings. I'm not getting any errors when invoking pdfFiller.fillForm, so I think it's working, but no file is being outputted into the directory I specified. I am logging if there is an error in the callback, but if not I just console log a success message. I'm always seeing the success message, but I don't get why it would not error out if it doesn't create the new PDF. I've also changed my directory permissions to 777, so that shouldn't be an issue.