Hi Roy,
I’m sorry to see you facing this issue.
I did some investigation in your api browser and it seems to be this document which is cause the error:
https://smartspending.prismic.io/api/v2/documents/search?ref=XtkGcRAAAB0ANTtf&pageSize=1&page=53#format=html
If you view the JSON version it causes an error
https://smartspending.prismic.io/api/v2/documents/search?ref=XtkGcRAAAB0ANTtf&pageSize=1&page=53#format=json
Try archiving this to see if that helps.
Thanks.