JavaScript error - 'invalid json in alfred' but I'm not outputting any json to the block

[FireWire]

First time I've run into this. I have a block called "Quote" and I've used it on one template but started getting this error when using it on a different template.

I removed all of my block markup but still getting the error.

It looks like the {alfred($block)} call is inserting JSON into the element

I feel like there's something I'm missing but can't figure out what would be causing it and not sure where to start looking.