errors in Firefox Developer Edition

What could be a reason of these errors?
I am getting these in Firefox Developer Edition.
On some (not all) scenes loaded from asset bundles, just few seconds after the scene gets loaded.
The build was released from 5.6.1 version.
In other browsers (FF quantum, MS edge) everything runs well.

An error occured running the Unity content on this page. See your browser JavaScript console for more info. The error was:
uncaught exception: abort("Assertion failed: undefined") at jsStackTrace (st17.asm.framework.unityweb:2:27465)
stackTrace (st17.asm.framework.unityweb:2:27636)
abort (st17.asm.framework.unityweb:4:33900)
assert (st17.asm.framework.unityweb:2:17465)
doCallback (st17.asm.framework.unityweb:2:143799)
done (st17.asm.framework.unityweb:2:143992)
done (st17.asm.framework.unityweb:2:127055)
UnityLoader["3c93c5e50c73eeb63a293b164746f438"]/reconcile [reconcile/transaction.onerror] (st17.asm.framework.unityweb:2:127104)

If this abort() is unexpected, build with -s ASSERTIONS=1 which can give more information.

 

I'm getting the exact same kind of error in Firefox Quantum (version 60). My game runs fine in Chrome and Edge.

UPDATE: Well, I feel silly as I've already solved the issue. Sorry then for bumping this thread - my problem, as revealed by a few other Google search results, was evidently stale cache with Firefox. It's possible the exception was thrown at an earlier state of my game, and that version of the webpage just got cached and wasn't being replaced. I cleared my cache and restarted Firefox, and the problem went away.