Fixes more errors

code/__HELPERS/_lists.dm

@@ -26,6 +26,7 @@
 #define reverseList(L) reverseRange(L.Copy())
 #define LAZYADDASSOC(L, K, V) if(!L) { L = list(); } L[K] += list(V);
 #define LAZYREMOVEASSOC(L, K, V) if(L) { if(L[K]) { L[K] -= V; if(!length(L[K])) L -= K; } if(!length(L)) L = null; }
+#define LAZYACCESSASSOC(L, I, K) L ? L[I] ? L[I][K] ? L[I][K] : null : null : null
 
 /// Passed into BINARY_INSERT to compare keys
 #define COMPARE_KEY __BIN_LIST[__BIN_MID]
@@ -294,6 +295,22 @@
 		if (total <= 0)
 			return item
 
+/proc/pickweightAllowZero(list/L) //The original pickweight proc will sometimes pick entries with zero weight.  I'm not sure if changing the original will break anything, so I left it be.
+	var/total = 0
+	var/item
+	for (item in L)
+		if (!L[item])
+			L[item] = 0
+		total += L[item]
+
+	total = rand(0, total)
+	for (item in L)
+		total -=L [item]
+		if (total <= 0 && L[item])
+			return item
+
+	return null
+
 //Picks a number of elements from a list based on weight.
 //This is highly optimised and good for things like grabbing 200 items from a list of 40,000
 //Much more efficient than many pickweight calls