I’m encountering these issues when trying to update an existing scene and publish it as a LAND. “Entity is not constructor.”
I had a similar problem awhile back using the online builder. The solution was clearing the browser cache in a specific order.
If you clear the cache while you are in the browser the active (and problematic) cache will remain.
My solution was to close all browser windows. Open a new browser window and clear the cache. Close that window and open a new one and try to publish your scene.
Also, I believe the online builder you are using is being deprecated and replaced by the visual code method, which is much better.
Here is the DCL tutorial that should help: https://www.youtube.com/watch?v=7wEJyAi0Qx0&list=PLAcRraQmr_GP_K8WN7csnKnImK4R2TgMA&index=5
All the best,