fix(frontend): onboarding runtime error (#10288)

## Changes 🏗️

<img width="800" alt="Screenshot 2025-07-02 at 16 43 08"
src="https://github.com/user-attachments/assets/d7cd0dd7-e671-4c5d-8ed9-6d8f56371ff5"
/>

During logout, the user state gets cleared but the onboarding provider
continues to run and tries to access onboarding.completedSteps on a null
object, causing a runtime error 😬

This mostly happens because onboarding is broken on local and dev ( the
onboarding agents don't work ), so I manually skip it after creating an
account, navigating to `/marketplace`. That makes me think that the
onboarding provider still thinks I need to onboard, and hence why this
error?

## Checklist 📋

#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
  - [x] Create a new user
- [x] Instead of completing onboarding, navigate to `/marketplace` via
browser URL
- [x] logout, login/logout again few times and you don't see runtime
errors

autogpt_platform/frontend/src/components/onboarding/onboarding-provider.tsx

@@ -45,6 +45,7 @@ export function useOnboarding(step?: number, completeStep?: OnboardingStep) {
     if (
       !completeStep ||
       !context.state ||
+      !context.state.completedSteps ||
       context.state.completedSteps.includes(completeStep)
     )
       return;
@@ -79,22 +80,32 @@ export default function OnboardingProvider({
 
   useEffect(() => {
     const fetchOnboarding = async () => {
-      const enabled = await api.isOnboardingEnabled();
-      if (!enabled && pathname.startsWith("/onboarding")) {
-        router.push("/marketplace");
-        return;
-      }
-      const onboarding = await api.getUserOnboarding();
-      setState((prev) => ({ ...onboarding, ...prev }));
+      try {
+        const enabled = await api.isOnboardingEnabled();
+        if (!enabled && pathname.startsWith("/onboarding")) {
+          router.push("/marketplace");
+          return;
+        }
+        const onboarding = await api.getUserOnboarding();
 
-      // Redirect outside onboarding if completed
-      // If user did CONGRATS step, that means they completed introductory onboarding
-      if (
-        onboarding.completedSteps.includes("CONGRATS") &&
-        pathname.startsWith("/onboarding") &&
-        !pathname.startsWith("/onboarding/reset")
-      ) {
-        router.push("/marketplace");
+        // Only update state if onboarding data is valid
+        if (onboarding) {
+          setState((prev) => ({ ...onboarding, ...prev }));
+
+          // Redirect outside onboarding if completed
+          // If user did CONGRATS step, that means they completed introductory onboarding
+          if (
+            onboarding.completedSteps &&
+            onboarding.completedSteps.includes("CONGRATS") &&
+            pathname.startsWith("/onboarding") &&
+            !pathname.startsWith("/onboarding/reset")
+          ) {
+            router.push("/marketplace");
+          }
+        }
+      } catch (error) {
+        console.error("Failed to fetch onboarding data:", error);
+        // Don't update state on error to prevent null access issues
       }
     };
     if (isUserLoading || !user) {
@@ -138,7 +149,12 @@ export default function OnboardingProvider({
 
   const completeStep = useCallback(
     (step: OnboardingStep) => {
-      if (!state || state.completedSteps.includes(step)) return;
+      if (
+        !state ||
+        !state.completedSteps ||
+        state.completedSteps.includes(step)
+      )
+        return;
 
       updateState({
         completedSteps: [...state.completedSteps, step],
@@ -148,7 +164,12 @@ export default function OnboardingProvider({
   );
 
   const incrementRuns = useCallback(() => {
-    if (!state || state.completedSteps.includes("RUN_AGENTS")) return;
+    if (
+      !state ||
+      !state.completedSteps ||
+      state.completedSteps.includes("RUN_AGENTS")
+    )
+      return;
 
     const finished = state.agentRuns + 1 >= 10;
     setNpsDialogOpen(finished);