Can't add items in Exhibitbuilder

Using a fresh install with latest software.
Seasons theme

1. created an exhibit
2. created a section
3. When adding a page, a box pops up saying "undefined"
4. The page is listed, but the same message occurs when trying to add an item.

That's something that we've seen elsewhere. More about it here

Fix will be released very soon.

And indeed, the fix in Omeka 1.5.3 is released!