fix(predict): Guards against undefined tags being returned from search endpoint (#24266)

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## **Description**

This PR fixes an issue where certain search queries in Predict would
return no results despite the API returning valid data.

**Reason for change:**
When users searched for terms like "nhl", the app would display no
results even though the search API returned valid events. Some events
had their tags field set to undefined instead of an empty array, causing
array method calls to throw. These errors were caught and silently
returned an empty array, resulting in "no results" displayed to users.

**Solution:**
Added defensive checks to safely handle undefined or non-array tags.
This ensures malformed events don't crash parsing and valid markets are
still displayed. Applied the same pattern to the markets field.

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CHANGELOG entry: Fixes issue where certain search queries in Predict
would return no results

## **Related issues**

Fixes:
[PRED-414](https://consensyssoftware.atlassian.net/browse/PRED-414)

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

## **Screenshots/Recordings**

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### **Before**

<img width="1320" height="2868" alt="image"
src="https://github.com/user-attachments/assets/71fd088c-2c30-45a7-b8bb-a8cc6f728002"
/>

### **After**

<img width="1320" height="2868" alt="image"
src="https://github.com/user-attachments/assets/33fbf6e6-7c3b-4cb4-8dd4-0702160ac331"
/>

## **Pre-merge author checklist**

- [x] I’ve followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.



<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Improves resilience of Polymarket market parsing and search results
handling.
> 
> - Guard `isSportEvent` against non-array `tags`; treat missing tags as
empty
> - In `sortMarkets`, treat non-array `markets` as empty and respect
`event.sortBy`
> - In `parsePolymarketEvents`, default missing `tags` to `[]`, ignore
inactive markets defensively, and continue parsing
> - In `getParsedMarketsFromPolymarketApi`, normalize response
(`events`/`data`) to arrays and, for search (`q`), return only events
with outcomes; remove extraneous logging
> - Tests: add cases for missing `markets` (returns `[]`) and missing
`tags` (yields empty tags)
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
0cbcfd6. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->



[PRED-414]:
https://consensyssoftware.atlassian.net/browse/PRED-414?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Author: kevinbluer

app/components/UI/Predict/providers/polymarket/utils.test.ts

@@ -2296,6 +2296,61 @@ describe('polymarket utils', () => {
       );
     });
 
+    it('returns empty array when search results omit markets', async () => {
+      const eventWithoutMarkets = {
+        ...mockEvent,
+        markets: undefined,
+      } as unknown as PolymarketApiEvent;
+
+      const mockResponse = {
+        events: [eventWithoutMarkets],
+      };
+
+      mockFetch.mockResolvedValue({
+        ok: true,
+        json: jest.fn().mockResolvedValue(mockResponse),
+      });
+
+      const params: GetMarketsParams = {
+        providerId: 'polymarket',
+        q: 'nhl',
+        limit: 10,
+        offset: 0,
+      };
+
+      const result = await getParsedMarketsFromPolymarketApi(params);
+
+      expect(result).toEqual([]);
+    });
+
+    it('returns empty tags when search results omit tags', async () => {
+      const eventWithoutTags = {
+        ...mockEvent,
+        tags: undefined,
+      } as unknown as PolymarketApiEvent;
+
+      const mockResponse = {
+        events: [eventWithoutTags],
+      };
+
+      mockFetch.mockResolvedValue({
+        ok: true,
+        json: jest.fn().mockResolvedValue(mockResponse),
+      });
+
+      const params: GetMarketsParams = {
+        providerId: 'polymarket',
+        q: 'nhl',
+        limit: 10,
+        offset: 0,
+      };
+
+      const result = await getParsedMarketsFromPolymarketApi(params);
+
+      expect(result).toHaveLength(1);
+      expect(result[0].tags).toEqual([]);
+    });
+
     it('handle different categories', async () => {
       const mockResponse = {
         data: [mockEvent],

app/components/UI/Predict/providers/polymarket/utils.ts

@@ -386,7 +386,9 @@ export const submitClobOrder = async ({
 };
 
 export const isSportEvent = (event: PolymarketApiEvent): boolean =>
-  event.tags.some((tag) => tag.slug === 'sports');
+  (Array.isArray(event.tags) ? event.tags : []).some(
+    (tag) => tag.slug === 'sports',
+  );
 
 export const isSpreadMarket = (market: PolymarketApiMarket): boolean =>
   market.sportsMarketType?.toLowerCase().includes('spread') ?? false;
@@ -562,7 +564,8 @@ export const sortMarkets = (
   event: PolymarketApiEvent,
   sortBy?: 'price' | 'ascending' | 'descending',
 ): PolymarketApiMarket[] => {
-  const { markets, sortBy: eventSortBy } = event;
+  const markets = Array.isArray(event.markets) ? event.markets : [];
+  const eventSortBy = event.sortBy;
 
   if (sortBy) {
     return sortMarketsByField(markets, sortBy);
@@ -605,28 +608,32 @@ export const parsePolymarketEvents = (
   sortMarketsBy?: 'price' | 'ascending' | 'descending',
 ): PredictMarket[] => {
   const parsedMarkets: PredictMarket[] = events.map(
-    (event: PolymarketApiEvent) => ({
-      id: event.id,
-      slug: event.slug,
-      providerId: 'polymarket',
-      title: event.title,
-      description: event.description,
-      image: event.icon,
-      status: event.closed
-        ? PredictMarketStatus.CLOSED
-        : PredictMarketStatus.OPEN,
-      recurrence: getRecurrence(event.series),
-      endDate: event.endDate,
-      category,
-      tags: event.tags.map((t) => t.label),
-      outcomes: sortMarkets(event, sortMarketsBy)
-        .filter((market: PolymarketApiMarket) => market.active !== false)
-        .map((market: PolymarketApiMarket) =>
-          parsePolymarketMarket(market, event),
-        ),
-      liquidity: event.liquidity,
-      volume: event.volume,
-    }),
+    (event: PolymarketApiEvent) => {
+      const tags = Array.isArray(event.tags) ? event.tags : [];
+
+      return {
+        id: event.id,
+        slug: event.slug,
+        providerId: 'polymarket',
+        title: event.title,
+        description: event.description,
+        image: event.icon,
+        status: event.closed
+          ? PredictMarketStatus.CLOSED
+          : PredictMarketStatus.OPEN,
+        recurrence: getRecurrence(event.series),
+        endDate: event.endDate,
+        category,
+        tags: tags.map((t) => t.label),
+        outcomes: sortMarkets(event, sortMarketsBy)
+          .filter((market: PolymarketApiMarket) => market?.active !== false)
+          .map((market: PolymarketApiMarket) =>
+            parsePolymarketMarket(market, event),
+          ),
+        liquidity: event.liquidity,
+        volume: event.volume,
+      };
+    },
   );
   return parsedMarkets;
 };
@@ -759,21 +766,21 @@ export const getParsedMarketsFromPolymarketApi = async (
   }
   const data = await response.json();
 
-  DevLogger.log('Polymarket response data:', data);
-
-  // Handle different response structures
-  const events = q ? data?.events : data?.data;
-
-  if (!events || !Array.isArray(events)) {
-    return [];
-  }
+  const eventsData = q ? data?.events : data?.data;
+  const events: PolymarketApiEvent[] = Array.isArray(eventsData)
+    ? eventsData
+    : [];
 
   const parsedMarkets: PredictMarket[] = parsePolymarketEvents(
     events,
     category,
     'price',
   );
 
+  if (q) {
+    return parsedMarkets.filter((m) => m.outcomes.length > 0);
+  }
+
   return parsedMarkets;
 };