Any Ideas? Panini Error 'toString' of null

Unfortunately, I’m not sure exactly when this error started occurring so it is making it difficult for me to find the error. I’m using Foundation SASS 6.2 and during the pages process, I’m getting this. I’m hoping someone else has seen this error or can point me in the direction of where to look to fix it? Pages do seem to be building okay. When (and why) would a toString be passed and why would it be null?

[12:23:53] Starting ‘pages’…
Panini: rendering error ocurred.
TypeError: Cannot read property ‘toString’ of null
at Panini.render (G:+Websites\bt-f6.2\node_modules\panini\lib\render.js:20:33)
at DestroyableTransform.Transform._read (G:+Websites\bt-f6.2\node_modules\readable-stream\lib_stream_transform.js:172:10)
at DestroyableTransform.Readable.read (G:+Websites\bt-f6.2\node_modules\readable-stream\lib_stream_readable.js:383:10)
at flow (G:+Websites\bt-f6.2\node_modules\readable-stream\lib_stream_readable.js:798:26)
at DestroyableTransform. (G:+Websites\bt-f6.2\node_modules\readable-stream\lib_stream_readable.js:656:7)
at DestroyableTransform.emit (events.js:311:20)
at DestroyableTransform.EventEmitter.emit (domain.js:505:15)
at onwriteDrain (G:+Websites\bt-f6.2\node_modules\readable-stream\lib_stream_writable.js:399:12)
at afterWrite (G:+Websites\bt-f6.2\node_modules\readable-stream\lib_stream_writable.js:387:5)
at onwrite (G:+Websites\bt-f6.2\node_modules\readable-stream\lib_stream_writable.js:380:7)

I apologize if this is something simple and I appreciate your taking the time to review this. Thanks so much!