fix crash

changelog.txt

@@ -5,6 +5,7 @@ Date: ????
     - Unconflicted big bags. Resolves https://github.com/pyanodon/pybugreports/issues/1570
     - Updated German locale (thanks, Spunk42!)
     - Updated science pack tech icons to match in game items
+    - Fixed spilling tailings ponds potentially crashing the game if left unattended for dozens of hours. Resolves https://github.com/pyanodon/pybugreports/issues/1450
 ---------------------------------------------------------------------------------------------------
 Version: 3.1.5
 Date: 2026-09-22

scripts/tailings-pond.lua

@@ -151,7 +151,12 @@ local function scorch_earth(pond)
                 local x, y = spiral(pond.lifetime_pollution_tiles_created)
                 x = math.floor(x + entity.position.x--[[@as number]]) - 1
                 y = math.floor(y + entity.position.y--[[@as number]]) - 1
-                if surface.get_tile(x, y).name ~= "polluted-ground" then
+                local next_tile = surface.get_tile(x, y)
+                if not next_tile.valid then
+                    surface.request_to_generate_chunks({x, y})
+                    surface.force_generate_chunk_requests()
+                end
+                if next_tile.name ~= "polluted-ground" then
                     tiles[#tiles + 1] = {name = "polluted-ground", position = {x = x, y = y}}
                 end
             end