I think there is a bug in the physics plugin names.
I was trying to serialize a physics enabled scene to a .babylon file, and then load the file to re-display the scene.
But I got an error while loading the .babylon file, it seems that something goes wrong when the loader tries to enable physics engine.
After looking into the serializer and loader, I found out that the physics plugin names are different from the names used in babylonFileLoader.ts.
For example, the AmmoJS plugin name is “AmmoJSPlugin” (defined in here), this name is also the one used by SceneSerializer, but in babylonFIleLoader, it uses the name “ammo” to deside which physics engine should be loaded.
I hope I make my point clear enough.