fix: clone lists to prevent outdated information

lib/src/list.js

@@ -8,6 +8,12 @@ const emptyLists = [[], [], [], []];
 
 const byNumber = (a, b) => a > b;
 const findForestType = (c) => types.forestType.find((f) => f.code === c);
+const getRecommendations = (forestType) => {
+  const [, lists] = Object.entries(recommendations).find(
+    (t) => t[0] === forestType,
+  );
+  return [...(lists || emptyLists)];
+};
 const nonresidents = (c) =>
   types.treeType.find((t) => t.code === c).nonresident;
 const residents = (c) => !types.treeType.find((t) => t.code === c).nonresident;
@@ -30,18 +36,14 @@ function list(location = {}) {
     throw new Error(`${forestType} is not valid`);
   }
 
-  const [, lists] = Object.entries(recommendations).find(
-    (t) => t[0] === forestType,
-  ) || [null, emptyLists];
+  const lists = getRecommendations(forestType);
 
   if (transitionForestType) {
     if (findForestType(transitionForestType) === undefined) {
       throw new Error(`${transitionForestType} is not valid`);
     }
 
-    const [, transitionLists] = Object.entries(recommendations).find(
-      (t) => t[0] === transitionForestType,
-    ) || [null, emptyLists];
+    const transitionLists = getRecommendations(transitionForestType);
 
     lists[0] = union(
       intersection(lists[0], transitionLists[0]),