Please give us the full error message as printed on the system console.
David, the site is here:
https://manxbirdphotography.co.uk/
What I was seeing in the devtools console was a successful load of
tree.json, but not even an
attempt to load
data1.json, which I found odd. But on a refresh, I started getting a 404 on
tree.json, as well.
Now I'm getting 404's even on
index.html, so I can't tell what's happening.
ETA: I suspect I've landed in the midst of the user's "delete and reupload." Will check again later....