You'll run into this when trying to e.g. find the new Plains village in spectator mode.
World gen is extremely slow and laggy, but when it generates something, it often has these errors in it.
The bug is temporary, relogging seems to fix it.
MC-140413
Chunks generate with none or low light values
Resolved
Duplicate
0
MightyPork
(Unassigned)
Unconfirmed
Minecraft 18w47b, Minecraft 18w48a, Minecraft 18w48b
Retrieved
Thank you for your report!
However, this issue is a Duplicate of MC-139038.
If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
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