fix(assets-controller): hardened error handling (#8389)

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## References

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## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Moderate risk because it changes how balance/detection/staked-balance
update callbacks propagate failures, potentially masking bugs but
preventing unhandled rejections from breaking polling ticks or
subscriptions.
> 
> **Overview**
> Improves resilience of `assets-controller` update pipelines by
**catching and logging errors inside subscription/polling callbacks**
instead of letting them throw/reject.
> 
> `AssetsController` now guards `onActiveChainsUpdated`, and
`RpcDataSource`/`StakedBalanceDataSource` wrap balance, detection, and
staked-balance update handlers so poll ticks can’t fail due to uncaught
exceptions or unhandled promise rejections.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
db04572. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: Kriys94

packages/assets-controller/src/AssetsController.ts

@@ -672,8 +672,8 @@ export class AssetsController extends BaseController<
   #unsubscribeBasicFunctionality: (() => void) | null = null;
 
   readonly #onActiveChainsUpdated: (
-    dataSourceId: string,
-    activeChains: ChainId[],
+    dataSourceName: string,
+    chains: ChainId[],
     previousChains: ChainId[],
   ) => void;
 
@@ -712,7 +712,14 @@ export class AssetsController extends BaseController<
       chains: ChainId[],
       previousChains: ChainId[],
     ): void => {
-      this.#handleActiveChainsUpdate(dataSourceName, chains, previousChains);
+      try {
+        this.#handleActiveChainsUpdate(dataSourceName, chains, previousChains);
+      } catch (error) {
+        log('Failed to handle active chains update', {
+          dataSourceName,
+          error,
+        });
+      }
     };
 
     this.#backendWebsocketDataSource = new BackendWebsocketDataSource({

packages/assets-controller/src/data-sources/RpcDataSource.ts

@@ -272,9 +272,14 @@ export class RpcDataSource extends AbstractDataSource<
       balanceFetcherMessenger,
       { pollingInterval: balanceInterval },
     );
-    this.#balanceFetcher.setOnBalanceUpdate(
-      this.#handleBalanceUpdate.bind(this),
-    );
+    // Polling controller awaits this callback; rejections must not become unhandled.
+    this.#balanceFetcher.setOnBalanceUpdate(async (result) => {
+      try {
+        await this.#handleBalanceUpdate(result);
+      } catch (error) {
+        log('Balance update handler failed', { error });
+      }
+    });
 
     // Initialize TokenDetector with polling interval
     const tokensApiClient = new TokensApiClient();
@@ -287,9 +292,14 @@ export class RpcDataSource extends AbstractDataSource<
         useExternalService: this.#useExternalService,
       },
     );
-    this.#tokenDetector.setOnDetectionUpdate(
-      this.#handleDetectionUpdate.bind(this),
-    );
+    // Sync throw in the detector would reject the poll tick if uncaught.
+    this.#tokenDetector.setOnDetectionUpdate((result) => {
+      try {
+        this.#handleDetectionUpdate(result);
+      } catch (error) {
+        log('Detection update handler failed', { error });
+      }
+    });
 
     this.#subscribeToNetworkController();
     this.#subscribeToTransactionEvents();

packages/assets-controller/src/data-sources/StakedBalanceDataSource.ts

@@ -192,10 +192,14 @@ export class StakedBalanceDataSource extends AbstractDataSource<
         this.#getProvider(hexChainId),
     });
 
-    // Wire the callback so polling results flow back to subscriptions
-    this.#stakedBalanceFetcher.setOnStakedBalanceUpdate(
-      this.#handleStakedBalanceUpdate.bind(this),
-    );
+    // Polling controller invokes this synchronously; keep failures inside the poll tick.
+    this.#stakedBalanceFetcher.setOnStakedBalanceUpdate((result) => {
+      try {
+        this.#handleStakedBalanceUpdate(result);
+      } catch (error) {
+        log('Staked balance update handler failed', { error });
+      }
+    });
 
     this.#messenger.subscribe(
       'TransactionController:transactionConfirmed',