From 3427c43df26c1588b4e85dcf5fc89e56251c6616 Mon Sep 17 00:00:00 2001
From: copperwater <aosdict@gmail.com>
Date: Sun, 23 Feb 2025 16:29:40 -0500
Subject: [PATCH] Guard against no themed rooms or fills being eligible to
 generate

The themed room code previously assumed that on any given level, at
least one room or fill would resolve as OK to generate there. However,
that's not a great assumption to make, and if it happened to be broken,
the first themed room or fill would arbitrarily be executed, even though
it wasn't eligible. Fix that by setting the initial pick to nil, and
raising an impossible if it's still nil after trying to choose a random
room.
---
 dat/themerms.lua | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/dat/themerms.lua b/dat/themerms.lua
index b7e0f1f0a..64c1b316e 100644
--- a/dat/themerms.lua
+++ b/dat/themerms.lua
@@ -936,7 +936,7 @@ function themerooms_generate()
       themerooms[actualrm].contents();
       return
    end
-   local pick = 1;
+   local pick = nil;
    local total_frequency = 0;
    for i = 1, #themerooms do
       if (type(themerooms[i]) ~= "table") then
@@ -957,6 +957,10 @@ function themerooms_generate()
          end
       end
    end
+   if pick == nil then
+      nh.impossible('no eligible themed rooms?')
+      return
+   end
    themerooms[pick].contents();
 end
 
@@ -995,7 +999,7 @@ function themeroom_fill(rm)
       end
       return
    end
-   local pick = 1;
+   local pick = nil;
    local total_frequency = 0;
    for i = 1, #themeroom_fills do
       if (type(themeroom_fills[i]) ~= "table") then
@@ -1016,6 +1020,10 @@ function themeroom_fill(rm)
          end
       end
    end
+   if pick == nil then
+      nh.impossible('no eligible themed room fills?')
+      return
+   end
    themeroom_fills[pick].contents(rm);
 end