From 38f74c845195e5661c690ebc9049e8a5267d2b75 Mon Sep 17 00:00:00 2001
From: taikedz <dch.tai@gmail.com>
Date: Fri, 29 Oct 2021 17:15:09 +0100
Subject: [PATCH] Fix to workaround #13 when a node seems undefined

---
 init.lua | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/init.lua b/init.lua
index 911b8cd..9b04200 100644
--- a/init.lua
+++ b/init.lua
@@ -90,15 +90,22 @@ function rspawn:newspawn(pos, radius)
         under = minetest.registered_nodes[under]
         over = minetest.registered_nodes[over]
 
-        if under.walkable
-         and not over.walkable
-         and not minetest.is_protected(anode, "")
-         and not (under.groups and under.groups.leaves ) -- no spawning on treetops!
-         and daylight_above(7, anode) then
-            if under.buildable_to then
-                validnodes[#validnodes+1] = {x=anode.x, y=anode.y-1, z=anode.z}
-            else
-                validnodes[#validnodes+1] = anode
+        if under == nil or over == nil then
+            -- `under` or `over` could be nil if a mod that defined that node was removed.
+            -- Not something this mod can resolve, and so we just ignore it.
+            rspawn:debug("Found an undefined node around "..minetest.pos_to_string(anode))
+
+        else
+            if under.walkable
+             and not over.walkable
+             and not minetest.is_protected(anode, "")
+             and not (under.groups and under.groups.leaves ) -- no spawning on treetops!
+             and daylight_above(7, anode) then
+                if under.buildable_to then
+                    validnodes[#validnodes+1] = {x=anode.x, y=anode.y-1, z=anode.z}
+                else
+                    validnodes[#validnodes+1] = anode
+                end
             end
         end
     end