diff --git a/advtrains_interlocking_mod/init.lua b/advtrains_interlocking_mod/init.lua
index 0cf4038..6770c27 100644
--- a/advtrains_interlocking_mod/init.lua
+++ b/advtrains_interlocking_mod/init.lua
@@ -1,15 +1,15 @@
 -- twi_mods/advtrains_interlocking_mod/init.lua
 -- Modify advtrains_interlocking
 -- Copyright (C) 2024  1F616EMO
 -- SPDX-License-Identifier: AGPL-3.0-or-later
 
 for _, name in ipairs({
-    "advtrains_interlocking:ds_danger",
-    "advtrains_interlocking:ds_free",
-    "advtrains_interlocking:ds_slow"
+    -- "advtrains_interlocking:ds_danger",
+    -- "advtrains_interlocking:ds_free",
+    -- "advtrains_interlocking:ds_slow"
 }) do
     twi_fx.override_group(name, {
         not_in_creative_inventory = 1,
         not_in_craft_guide = 1,
     })
 end
diff --git a/advtrains_moreslopes_mod/init.lua b/advtrains_moreslopes_mod/init.lua
index b69feba..a7ed71a 100644
--- a/advtrains_moreslopes_mod/init.lua
+++ b/advtrains_moreslopes_mod/init.lua
@@ -1,35 +1,35 @@
 -- twi_mods/advtrains_moreslopes_mod/init.lua
 -- Modify advtrains_moreslopes
 -- Copyright (C) 2024  1F616EMO
 -- SPDX-License-Identifier: AGPL-3.0-or-later
 
-core.register_craft({
-    type = "shapeless",
-    recipe = { "advtrains:dtrack_more_slopeplacer" },
-    output = "advtrains:dtrack_slopeplacer",
-})
+-- core.register_craft({
+--     type = "shapeless",
+--     recipe = { "advtrains:dtrack_more_slopeplacer" },
+--     output = "advtrains:dtrack_slopeplacer",
+-- })
 
-core.register_craft({
-    type = "shapeless",
-    recipe = { "advtrains:dtrack_slopeplacer" },
-    output = "advtrains:dtrack_more_slopeplacer",
-})
+-- core.register_craft({
+--     type = "shapeless",
+--     recipe = { "advtrains:dtrack_slopeplacer" },
+--     output = "advtrains:dtrack_more_slopeplacer",
+-- })
 
-core.override_item("advtrains:dtrack_slopeplacer", {
-    description = ">= 1:3 " .. core.registered_items["advtrains:dtrack_slopeplacer"].description,
-})
+-- core.override_item("advtrains:dtrack_slopeplacer", {
+--     description = ">= 1:3 " .. core.registered_items["advtrains:dtrack_slopeplacer"].description,
+-- })
 
-core.override_item("advtrains:dtrack_more_slopeplacer", {
-    description = "<= 1:4 " .. core.registered_items["advtrains:dtrack_more_slopeplacer"].description,
-})
+-- core.override_item("advtrains:dtrack_more_slopeplacer", {
+--     description = "<= 1:4 " .. core.registered_items["advtrains:dtrack_more_slopeplacer"].description,
+-- })
 
 for i = 4, 8 do
     for j = 1, i do
         local name = "advtrains:dtrack_more_vst" .. i .. j
 
         core.override_item(name, {
             walkable = true,
             collision_box = core.registered_items[name].selection_box,
         })
     end
 end
diff --git a/twi_fx/init.lua b/twi_fx/init.lua
index 38076de..4cd0f39 100644
--- a/twi_fx/init.lua
+++ b/twi_fx/init.lua
@@ -1,53 +1,54 @@
 -- twi_mods/twi_fx/init.lua
 -- Common functions
 --[[
     Copyright © 2024 1F616EMO
 
     Permission is hereby granted, free of charge, to any person obtaining a copy
     of this software and associated documentation files (the "Software"), to deal
     in the Software without restriction, including without limitation the rights
     to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     copies of the Software, and to permit persons to whom the Software is
     furnished to do so, subject to the following conditions:
 
     The above copyright notice and this permission notice shall be included in
     all copies or substantial portions of the Software.
 
     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     THE SOFTWARE.
 ]]
 
 twi_fx = {}
 
 function twi_fx.register_all_stairsplus(modname, name)
     local nodename = modname .. ":" .. name
     local def = table.copy(core.registered_nodes[nodename])
 
     def.is_ground_content = false
     def.sunlight_propagates = true
 
     stairsplus:register_all(modname, name, nodename, def)
 end
 
 function twi_fx.override_group(name, new_groups)
+    assert(core.registered_items[name], "Item " .. name .. " does not exist")
     local groups = table.copy(core.registered_items[name].groups or {})
     for k, v in pairs(new_groups) do
         groups[k] = v == 0 and nil or v
     end
     core.override_item(name, {
         groups = groups,
     })
 end
 
 twi_fx.register_on_chat_message =
     core.global_exists("beerchat")
     and beerchat.register_on_chat_message
     or core.register_on_chat_message
 
 -- Limit that out hardware can bear
 twi_fx.ADVTRAINS_MAX_TRAIN_SPEED = 30