I've managed to reproduce the issue on Win2k8R2. It's coming from ImageMagick not being installed/configured correctly.
These are the steps I took to fix the issue:
Go out and install the latest version of ImageMagick
After running the installer make sure that you close the command prompt from which you are running NodeBB.
Open a new command prompt and rerun node app.js
The problem should be fixed! 🙂resolved.png