It appears that if the "Chrome" object is defined for a recipe, it also needs a viewport Width / Height. I am unclear how this object got set to begin width as I am almost exclusively using the editor.
Generates Error:
chrome": {
"printBackground": true
},
Does not generate error / Works:
"chrome": {
"printBackground": true,
"viewportHeight": 1024,
"viewportWidth": 1024
},
Not a pressing issue as this works for what I am doing. Might be nice to have a default width / height if not specified.