diff --git a/elixir.lua b/elixir.lua
index 920e963..1ac8c56 100644
--- a/elixir.lua
+++ b/elixir.lua
@@ -108,6 +108,9 @@ for _, name in pairs(elixir_ingredients) do
 	if not item then
 		item = minetest.registered_nodes[name]
 	end
+	if not item then
+		break
+	end
 	if item then
 		if item.groups then
 			groups = table.copy(item.groups)
diff --git a/goblin.lua b/goblin.lua
index 99b12a9..b30519a 100644
--- a/goblin.lua
+++ b/goblin.lua
@@ -2,7 +2,7 @@
 -- GOBLINS
 ---------------------------------------------------------------
 
-local spawn_frequency = 250  -- 250
+local spawn_frequency = 500  -- 500
 local dig_freq = 5  -- 5
 local trap_freq = 25  -- 25
 local torch_freq = 2  -- 2
diff --git a/spec_bomb.lua b/spec_bomb.lua
index a6d36f5..e06de2d 100644
--- a/spec_bomb.lua
+++ b/spec_bomb.lua
@@ -120,6 +120,10 @@ local nodes = {{'default:sandstone', 'default:sandstone_block'}, {'default:wood'
 for _, node in pairs(nodes) do
 	local node_name = node[1]
 	local comp = node[2] or node_name
+	if not minetest.registered_items[node_name] or (not minetest.registered_items[comp] and not comp:find('^fun_caves')) then
+		break
+	end
+
 	local node_texture = minetest.registered_items[node_name].tiles
 	if type(node_texture) == 'table' then
 		node_texture = node_texture[1]
@@ -197,6 +201,10 @@ local function default_rightclick(pos, node, clicker, itemstack, pointed_thing)
 end
 
 for _, node in pairs(mass_nodes) do
+	if not minetest.registered_items[node] then
+		break
+	end
+
 	minetest.override_item(node, {on_rightclick = function(pos, node, clicker, itemstack, pointed_thing)
 		local tool = itemstack:get_name()
 		if not mass_tools[tool] then
diff --git a/treegen.lua b/treegen.lua
index 30f39f0..2e4cea5 100644
--- a/treegen.lua
+++ b/treegen.lua
@@ -355,7 +355,7 @@ fun_caves.treegen = function(minp, maxp, data, p2data, area, node)
 					end
 
 					if data[ivm] ~= node['air'] and data[ivm] ~= node['fun_caves:weightless_water'] then
-						if math_random(100) == 1 then
+						if math_random(200) == 1 then
 							data[ivm] = node['fun_caves:sap']
 						elseif math_random(1000) == 1 then
 							data[ivm] = node['fun_caves:tree_mineral']