From 29e9d36f368ffce34e1de0e35625ade14045510d Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Mon, 30 Mar 2026 16:19:17 +0000
Subject: [PATCH 1/2] Fix: null-guard API callbacks to prevent TypeError on
 network failure

When _getJSON fails it calls callback(null). Three callers were reading
properties on that null value, causing unhandled TypeErrors in production:

- ZEEGUU-WEB-BX (80 events, 62 users): App.js getUserPreferences callback
  reading preferences["audio_exercises"] on null
- ZEEGUU-WEB-BP (75 events, 53 users): ProgressContext.js getDailyStreak
  callback reading data.daily_streak on null
- ZEEGUU-WEB-DN: useSelectInterest.js spreading null availableTopics /
  subscribedTopics into newAllTopics

Fix: add early-return guard (if !data/preferences) in each callback,
and prevent null from entering state for the topics arrays.

Fixes ZEEGUU-WEB-BX, ZEEGUU-WEB-BP, ZEEGUU-WEB-DN

https://claude.ai/code/session_01KZumy5REz1to8tCJEmuD5s
---
 src/App.js                      | 1 +
 src/contexts/ProgressContext.js | 1 +
 src/hooks/useSelectInterest.js  | 4 ++--
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/App.js b/src/App.js
index c2d032160..2db6545c7 100644
--- a/src/App.js
+++ b/src/App.js
@@ -263,6 +263,7 @@ function App() {
 
     // TODO: Should this be moved to Settings.loadUsrePreferences?
     api.getUserPreferences((preferences) => {
+      if (!preferences) return;
       SessionStorage.setAudioExercisesEnabled(
         preferences["audio_exercises"] === undefined || preferences["audio_exercises"] === "true",
       );
diff --git a/src/contexts/ProgressContext.js b/src/contexts/ProgressContext.js
index 65099cbda..22173ec23 100644
--- a/src/contexts/ProgressContext.js
+++ b/src/contexts/ProgressContext.js
@@ -20,6 +20,7 @@ function ProgressProvider({ children }) {
   useEffect(() => {
     if (!userDetails?.learned_language) return;
     api.getDailyStreak((data) => {
+      if (!data) return;
       setDaysPracticed(data.daily_streak);
     });
   }, [userDetails?.learned_language]);
diff --git a/src/hooks/useSelectInterest.js b/src/hooks/useSelectInterest.js
index 39a06d1c7..643ba1904 100644
--- a/src/hooks/useSelectInterest.js
+++ b/src/hooks/useSelectInterest.js
@@ -10,11 +10,11 @@ export default function useSelectInterest(api) {
 
   useEffect(() => {
     api.getAvailableTopics((data) => {
-      setAvailableTopics(data);
+      if (data) setAvailableTopics(data);
     });
 
     api.getSubscribedTopics((data) => {
-      setSubscribedTopics(data);
+      if (data) setSubscribedTopics(data);
     });
 
     //custom interest filters

From b4f80044ea80b29190024e750a7722c0cdfbe98c Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Mon, 30 Mar 2026 16:20:17 +0000
Subject: [PATCH 2/2] Refactor: null-guard remaining callback and simplify
 isSubscribed (boy scout rule)

- Guard getSubscribedSearchers callback against null for consistency with
  the other two topic callbacks fixed in the previous commit
- Simplify isSubscribed: replace .map().includes() + ternary with .some()

https://claude.ai/code/session_01KZumy5REz1to8tCJEmuD5s
---
 src/hooks/useSelectInterest.js | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/hooks/useSelectInterest.js b/src/hooks/useSelectInterest.js
index 643ba1904..d7e7c21d6 100644
--- a/src/hooks/useSelectInterest.js
+++ b/src/hooks/useSelectInterest.js
@@ -19,7 +19,7 @@ export default function useSelectInterest(api) {
 
     //custom interest filters
     api.getSubscribedSearchers((data) => {
-      setSubscribedSearches(data);
+      if (data) setSubscribedSearches(data);
     });
   }, [api]);
 
@@ -68,11 +68,7 @@ export default function useSelectInterest(api) {
   }
 
   function isSubscribed(topic) {
-    return subscribedTopics
-      .map((subscribedTopic) => subscribedTopic.id)
-      .includes(topic.id)
-      ? true
-      : false;
+    return subscribedTopics.some((t) => t.id === topic.id);
   }
 
   function subscribeToEmail(search) {