Digging light sources leaves dynamic light behind briefly

This helps to bridge the latency gap between the dig completing
on the client side, and the server sending the result, which might
include adding dynamic lights from a now-handheld light emitter,
e.g. for torches or lanterns.

mods/nc_api_active/dynalight.lua

@@ -229,3 +229,15 @@ function nodecore.dynamic_shade_add(pos, above)
 			}, above - 1)
 	end
 end
+
+-- When digging a node that emits light when placed, and would
+-- emit light when held, there can be a brief flicker of darkness
+-- when MT predicts the dug node is gone but the dynamic light
+-- hasn't been send to the player yet.
+
+nodecore.register_on_register_item(function(_, def)
+		if def.light_source and def.light_source > 0
+		and def.node_dig_prediction == nil then
+			def.node_dig_prediction = modname .. ":light" .. def.light_source
+		end
+	end)