Potential fix for pull request finding 'CodeQL / Prototype-polluting assignment'

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: Kriys94

packages/assets-controller/src/AssetsController.ts

@@ -2746,13 +2746,16 @@ export class AssetsController extends BaseController<
     chainIds: ChainId[],
     assetTypes: AssetType[],
   ): Record<AccountId, Record<Caip19AssetId, Asset>> {
-    const result: Record<AccountId, Record<Caip19AssetId, Asset>> = {};
+    const result = Object.create(null) as Record<
+      AccountId,
+      Record<Caip19AssetId, Asset>
+    >;
     // Convert to Sets for O(1) lookups
     const chainIdSet = new Set(chainIds);
     const assetTypeSet = new Set(assetTypes);
 
     for (const account of accounts) {
-      result[account.id] = {};
+      result[account.id] = Object.create(null) as Record<Caip19AssetId, Asset>;
 
       const accountBalances = this.state.assetsBalance[account.id] ?? {};