Fix gravel not breaking to chips

nc_sky_inject/init.lua

@@ -8,3 +8,29 @@ local ntgr = nodecore.tree_growth_rate
 function nodecore.tree_growth_rate(pos)
   return ntgr(pos)*10
 end
+
+nodecore.register_craft({
+  label = "break gravel to chips",
+		action = "pummel",
+		nodes = {
+			{match = "nc_terrain:gravel_loose", replace = "nc_terrain:sand"}
+		},
+		items = {
+			{name = modname .. ":chip", count = 4, scatter = 5}
+		},
+		toolgroups = {cracky = 2},
+		itemscatter = 5
+	})
+
+nodecore.register_craft({
+  label = "break packed gravel to chips",
+		action = "pummel",
+		nodes = {
+			{match = "nc_terrain:gravel", replace = "nc_terrain:sand"}
+		},
+		items = {
+			{name = modname .. ":chip", count = 2, scatter = 5}
+		},
+		toolgroups = {cracky = 2},
+		itemscatter = 5
+	})