This is a very common issue that gets more and more embarrassing :) Judging from the stack trace, in your case it looks like your main collection has an embedded game object referencing a collection proxy file that points to the original main collection.
Expected behaviour
Start the game
Actual behaviour
The error message: java.lang.AssertionError: Assert failed: Cycle detected on node type editor.collection/CollectionNode and output :build-targets (not (contains? (:in-production ctx) [node-id label]))
Steps to reproduce
Having a collection proxy point to the collection it is currently in.
This actually doesn't seem to be the problem. I get this error each time if have a specific collection in another collection.
This is a very common issue that gets more and more embarrassing :) Judging from the stack trace, in your case it looks like your main collection has an embedded game object referencing a collection proxy file that points to the original main collection.