From 76ba6e9b5c272ef99af6ed5d1183073f32e03a7b Mon Sep 17 00:00:00 2001
From: plule <630159+plule@users.noreply.github.com>
Date: Tue, 3 Oct 2023 22:53:49 +0200
Subject: [PATCH] Fix nil access of tiletype and tileblock

---
 changelog.txt      |  1 +
 suspendmanager.lua | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/changelog.txt b/changelog.txt
index f7a2e75445..3c4fcc1e01 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -31,6 +31,7 @@ Template for new versions:
 ## New Features
 
 ## Fixes
+- `suspendmanager`: fix errors when constructing near the map edge
 
 ## Misc Improvements
 
diff --git a/suspendmanager.lua b/suspendmanager.lua
index a3d751d349..283d99234f 100644
--- a/suspendmanager.lua
+++ b/suspendmanager.lua
@@ -308,13 +308,20 @@ end
 --- Check if the tile can be walked on
 ---@param pos coord
 local function walkable(pos)
-    return dfhack.maps.getTileBlock(pos).walkable[pos.x % 16][pos.y % 16] > 0
+    local tileblock = dfhack.maps.getTileBlock(pos)
+    return tileblock and tileblock.walkable[pos.x % 16][pos.y % 16] > 0
 end
 
 --- Check if the tile is suitable tile to stand on for construction (walkable & not a tree branch)
 ---@param pos coord
 local function isSuitableAccess(pos)
     local tt = dfhack.maps.getTileType(pos)
+
+    if not tt then
+        -- no tiletype, likely out of bound
+        return false
+    end
+
     local attrs = df.tiletype.attrs[tt]
     if attrs.shape == df.tiletype_shape.BRANCH or attrs.shape == df.tiletype_shape.TRUNK_BRANCH then
         -- Branches can be walked on, but most of the time we can assume that it's not a suitable access.
@@ -425,6 +432,7 @@ local function tileHasSupportFloor(pos)
         local attrs = df.tiletype.attrs[tt]
         if TILETYPE_SHAPE_FLOOR_SUPPORT[attrs.shape] then return true end
     end
+    return false
 end
 
 local function tileHasSupportBuilding(pos)