Protect against null result

lib/api.js

@@ -46,16 +46,16 @@ const createZeroTrustList = (name, items) =>
 
 /**
  * Patches an existing list. Remove/append entries to the list.
- * 
+ *
  * API docs: https://developers.cloudflare.com/api/operations/zero-trust-lists-patch-zero-trust-list
  * @param {string} listId The ID of the list to patch
  * @param {Object} patch The changes to make
  * @param {string[]} patch.remove A list of the item values you want to remove.
  * @param {Object[]} patch.append Items to add to the list.
  * @param {string} patch.append[].value The domain of an entry.
- * @returns 
- */  
-const patchExistingList = (listId, patch) => 
+ * @returns
+ */
+const patchExistingList = (listId, patch) =>
   requestGateway(`/lists/${listId}`, {
     method: "PATCH",
     body: JSON.stringify(patch),
@@ -75,9 +75,9 @@ export const synchronizeZeroTrustLists = async (items) => {
 
   console.log("Checking existing lists...");
   const { result: lists } = await getZeroTrustLists();
-  const cgpsLists = lists.filter(({ name }) => name.startsWith("CGPS List"));
+  const cgpsLists = lists?.filter(({ name }) => name.startsWith("CGPS List")) || [];
   console.log(`Found ${cgpsLists.length} existing lists. Calculating diffs...`);
-  
+
   const domainsByList = {};
   // Do this sequentially to avoid rate-limits
   for (const list of cgpsLists) {
@@ -293,9 +293,9 @@ export const createZeroTrustRule = async (wirefilterExpression, name = "CGPS Fil
  * Updates a Zero Trust rule.
  *
  * API docs: https://developers.cloudflare.com/api/operations/zero-trust-gateway-rules-update-zero-trust-gateway-rule
- * @param {number} id The ID of the rule to be updated. 
+ * @param {number} id The ID of the rule to be updated.
  * @param {string} wirefilterExpression The expression to be used for the rule.
- * @param {string} name The name of the rule. 
+ * @param {string} name The name of the rule.
  * @param {string[]} filters The filters to be used for the rule.
  * @returns {Promise<Object>}
  */