I'm honestly not sure if this is a bug or if it's part of a mod, but researching this subject hasn't yielded me any answers yet. My map is dotted with what looks to be random void holes. It's definitely not a chunk loading error... or at least not the type I've seen before. The first time I came across one, I watched a cow approach the edge and turn into steaks upon entering. Later I was tunneling downwards to do some branch mining and while hearing the sounds of what I thought was lava, I broke the wall and out came... void water? (Sorry, no screenshot.) Basically, it came out in the same manner as lava or water, but it was a semi-transparent black. Again, I thought this was an error. I tried sticking a torch inside (it fell away) and then an empty bucket, which came back with regular water. The blackness I could see beyond the hole was that void blackness, not like the regular cavern darkness. Ended up plugging the hole with cobblestone.
Anyone else experience this? If it's a mod, it's a feature I really hate, and I'd like to know what to do to turn it off. And if it's a bug... how do I fix it? This same thing happened when I spawned a new map. My browser is up to date and I'm playing the latest stable version. Any suggestions would be appreciated.