A new bug was introduced in the last 24 hours causing the SpriteManager constructor to throw an error. It is occurring on Morterra: https://morterra.com
I checked the Playground example from the official docs and it has the same bug:
https://www.babylonjs-playground.com/#9RI8CG#0
I’m guessing it’s from the latest commit 18hr ago by @sebavan:
Going to start looking for a fix but I figured I would go ahead and let everyone know it exists!
I confirm the same result on my side at this moment. In my scene that was working perfectly as of yesterday and in all playground examples of SpriteManager. Calling The sprite manager currently prevents the scene from loading. Hoping for a quick fix. Thx.
Same. Worst part for me is I can’t just revert to the stable/cdn version because I need some key functions only available in the preview version, but the preview version breaks every once in a while 
Sry to hear you are spending time on this. Luckily, I’m only still building my alpha (to come shortly) but I still have other work to do, so I choose to simply leave this aside until it’s stable again (or reworked, I don’t know). The only thing that worries me a little is how this sort of bug could affect a final version in production. I have to admit I know little of the sprite manager integration in the framework. I found it just easy to use as such for my needs.
Edit: And then, in my case I could reverse to the stable version (and would also use this version in production). But part of my project is also to follow and try to understand the potential issues and the response in a development phase. So, as I said I will continue my work on other parts, keep an eye on this and wait and see…
This PR should correct the problem:
Thank you very much!
fix will be on the cdn in about 1 hour, sorry for that 
@morterra should be all good now, thanks a lot for reporting it.