update error handling in ExchangeApiKeysController and StakingService to return null and zero respectively

Author: flopez7

packages/apps/reputation-oracle/server/src/modules/exchange-api-keys/exchange-api-keys.controller.ts

@@ -54,12 +54,12 @@ export class ExchangeApiKeysController {
   @Get('/')
   async retrieveEnrolledApiKeys(
     @Req() request: RequestWithUser,
-  ): Promise<EnrolledApiKeyDto> {
+  ): Promise<EnrolledApiKeyDto | null> {
     const userId = request.user.id;
 
     const apiKey = await this.exchangeApiKeysService.retrieve(userId);
     if (!apiKey) {
-      throw new ExchangeApiKeyNotFoundError(userId);
+      return null;
     }
 
     return {

packages/apps/reputation-oracle/server/src/modules/staking/staking.service.spec.ts

@@ -10,10 +10,7 @@ import { SupportedExchange } from '@/common/constants';
 import { StakingConfigService, Web3ConfigService } from '@/config';
 import { type ExchangeClient } from '@/modules/exchange';
 import { ExchangeClientFactory } from '@/modules/exchange/exchange-client.factory';
-import {
-  ExchangeApiKeyNotFoundError,
-  ExchangeApiKeysService,
-} from '@/modules/exchange-api-keys';
+import { ExchangeApiKeysService } from '@/modules/exchange-api-keys';
 import { UserEntity, UserNotFoundError, UserRepository } from '@/modules/user';
 import { WalletWithProvider, Web3Service } from '@/modules/web3';
 import { mockWeb3ConfigService } from '@/modules/web3/fixtures';
@@ -72,12 +69,12 @@ describe('StakingService', () => {
 
   describe('getExchangeStakedBalance', () => {
     const userId = faker.number.int();
-    it('throws ExchangeApiKeyNotFoundError when user has no exchange keys', async () => {
+    it('returns 0 when user has no exchange keys', async () => {
       mockExchangeApiKeysService.retrieve.mockResolvedValueOnce(null);
 
       await expect(
         stakingService.getExchangeStakedBalance(userId),
-      ).rejects.toBeInstanceOf(ExchangeApiKeyNotFoundError);
+      ).resolves.toBe(0);
     });
 
     it('returns balance fetched from exchange client', async () => {

packages/apps/reputation-oracle/server/src/modules/staking/staking.service.ts

@@ -6,10 +6,7 @@ import { SupportedExchange } from '@/common/constants';
 import { StakingConfigService, Web3ConfigService } from '@/config';
 import logger from '@/logger';
 import { ExchangeClientFactory } from '@/modules/exchange/exchange-client.factory';
-import {
-  ExchangeApiKeyNotFoundError,
-  ExchangeApiKeysService,
-} from '@/modules/exchange-api-keys';
+import { ExchangeApiKeysService } from '@/modules/exchange-api-keys';
 import { UserNotFoundError, UserRepository } from '@/modules/user';
 import { Web3Service } from '@/modules/web3';
 import { formatStake } from '@/utils/stake';
@@ -34,7 +31,7 @@ export class StakingService {
   async getExchangeStakedBalance(userId: number): Promise<number> {
     const apiKeys = await this.exchangeApiKeysService.retrieve(userId);
     if (!apiKeys) {
-      throw new ExchangeApiKeyNotFoundError(userId);
+      return 0;
     }
 
     const client = await this.exchangeClientFactory.create(