Should be much better now.
BUT this happens because you have a broken XREF.
At the moment the builder is not able to notify you when you have changed a table, or a field that is already instancied in a FK or a XREF.
This is because I use JSON encoding to store the XREF config, and so is it a bit difficult to make a validator on that, but this is on the roadmap for a better ergonomy for you.
So, you can now build and test in sandbox, but check carefully the last TABLES / FIELDS you might have deleted because some was instancied in a XREF.
You might have an ignored XREF somewhere.
Cannot tell you more at the moment, but this is solved now.
Your previous problem was the same, but blocking in somewhere else. It was concerning a Foreign Key.