diff --git a/src/backend/platforms/metaculus/api.ts b/src/backend/platforms/metaculus/api.ts
index 760b6b0..d8e2ad8 100644
--- a/src/backend/platforms/metaculus/api.ts
+++ b/src/backend/platforms/metaculus/api.ts
@@ -106,6 +106,9 @@ const questionSchema = {
       properties: {
         ...commonProps,
         ...pageProps,
+      },
+      optionalProperties: {
+        ...optionalPageProps,
         sub_questions: {
           elements: {
             properties: {
@@ -116,9 +119,6 @@ const questionSchema = {
           },
         },
       },
-      optionalProperties: {
-        ...optionalPageProps,
-      },
       additionalProperties: true,
     },
     // we're not interested in claims currently (but we should be?)
diff --git a/src/backend/platforms/metaculus/index.ts b/src/backend/platforms/metaculus/index.ts
index 526fca6..8dbfd63 100644
--- a/src/backend/platforms/metaculus/index.ts
+++ b/src/backend/platforms/metaculus/index.ts
@@ -74,7 +74,10 @@ async function apiQuestionToFetchedQuestions(
   if (apiQuestion.type === "group") {
     await sleep(SLEEP_TIME);
     const apiQuestionDetails = await fetchSingleApiQuestion(apiQuestion.id);
-    return apiQuestion.sub_questions
+    if (apiQuestionDetails.type !== "group") {
+      throw new Error("Expected `group` type"); // shouldn't happen, this is mostly for typescript
+    }
+    return (apiQuestionDetails.sub_questions || [])
       .filter((q) => !skip(q))
       .map((sq) => {
         const tmp = buildFetchedQuestion(sq);