fix: fixes debug_traceBlockByNumber response to not be null for a transaction with no internal calls

packages/relay/src/lib/debug.ts

@@ -291,9 +291,9 @@ export class DebugImpl implements Debug {
         // The actions endpoint does not return input and output for the calls so we get them from another endpoint
         // The first one is excluded because we take its input and output from the contracts/results/{transactionIdOrHash} endpoint
         const contract =
-          index !== 0 && (
-            action.call_operation_type === CallType.CREATE || action.call_operation_type === CallType.CREATE2
-          ) && action.to
+          index !== 0 &&
+          (action.call_operation_type === CallType.CREATE || action.call_operation_type === CallType.CREATE2) &&
+          action.to
             ? await this.mirrorNodeClient.getContract(action.to, requestDetails)
             : undefined;
 
@@ -459,7 +459,7 @@ export class DebugImpl implements Debug {
     transactionHash: string,
     tracerConfig: ICallTracerConfig,
     requestDetails: RequestDetails,
-  ): Promise<CallTracerResult | null> {
+  ): Promise<CallTracerResult> {
     try {
       const [actionsResponse, transactionsResponse] = await Promise.all([
         this.mirrorNodeClient.getContractsResultsActions(transactionHash, requestDetails),
@@ -473,9 +473,6 @@ export class DebugImpl implements Debug {
         throw predefined.RESOURCE_NOT_FOUND(`Failed to retrieve contract results for transaction ${transactionHash}`);
       }
 
-      // return empty array if no actions
-      if (actionsResponse.length === 0) return null;
-
       const { call_type: type } = actionsResponse[0];
       const formattedActions = await this.formatActionsResult(actionsResponse, requestDetails);
 
@@ -510,7 +507,7 @@ export class DebugImpl implements Debug {
         // if we have more than one call executed during the transactions we would return all calls
         // except the first one in the sub-calls array,
         // therefore we need to exclude the first one from the actions response
-        calls: tracerConfig?.onlyTopCall || actionsResponse.length === 1 ? undefined : formattedActions.slice(1),
+        calls: tracerConfig?.onlyTopCall || actionsResponse.length === 1 ? [] : formattedActions.slice(1),
       };
     } catch (e) {
       throw this.common.genericErrorHandler(e);

packages/relay/tests/lib/debug.spec.ts

@@ -408,7 +408,7 @@ describe('Debug API Test Suite', async function () {
             gasUsed: '0x3a980',
             input: '0x1',
             output: '0x2',
-            calls: undefined,
+            calls: [],
           };
           const result = await debugService.traceTransaction(
             transactionHash,
@@ -418,17 +418,31 @@ describe('Debug API Test Suite', async function () {
 
           expect(result).to.deep.equal(expectedResult);
         });
-
-        it('Should return empty array if no actions found', async function () {
-          restMock.onGet(CONTARCTS_RESULTS_ACTIONS).reply(200, JSON.stringify({ actions: [] }));
+        it('should return empty calls array when using callTracer with single action (no internal calls)', async function () {
+          const singleActionResponse = {
+            actions: [contractsResultsActionsResult.actions[0]], // Only the root action
+          };
+          restMock.onGet(CONTARCTS_RESULTS_ACTIONS).reply(200, JSON.stringify(singleActionResponse));
 
           const result = await debugService.traceTransaction(
             transactionHash,
             tracerObjectCallTracerFalse,
             requestDetails,
           );
 
-          expect(result).to.be.null;
+          const expectedResult = {
+            type: 'CREATE',
+            from: accountsResult.evm_address,
+            to: contractResult.evm_address,
+            value: '0x0',
+            gas: '0x493e0',
+            gasUsed: '0x3a980',
+            input: '0x1',
+            output: '0x2',
+            calls: [],
+          };
+
+          expect(result).to.deep.equal(expectedResult);
         });
       });
 

packages/server/tests/acceptance/debug.spec.ts

@@ -446,7 +446,8 @@ describe('@debug API Acceptance Tests', function () {
           accounts[0].address,
           parentContractAddress,
         );
-        expect(result).to.not.have.property('calls');
+        expect(result).to.have.property('calls');
+        expect(result.calls).to.be.an('array').that.is.empty;
       });
     });
 

packages/server/tests/acceptance/rpc_batch3.spec.ts

@@ -1133,6 +1133,7 @@ describe('@api-batch-3 RPC Server Acceptance Tests', function () {
         gasUsed: '0x249f00',
         input: '',
         output: '',
+        calls: [],
       };
       const successResultCreateWithDepth = {
         ...defaultResponseFields,
@@ -1152,6 +1153,7 @@ describe('@api-batch-3 RPC Server Acceptance Tests', function () {
       const successResultCall = {
         ...defaultResponseFields,
         type: 'CALL',
+        calls: [],
       };
       const successResultCallWithDepth = {
         ...successResultCall,
@@ -1173,12 +1175,14 @@ describe('@api-batch-3 RPC Server Acceptance Tests', function () {
         error: 'CONTRACT_EXECUTION_EXCEPTION',
         revertReason: 'INSUFFICIENT_STACK_ITEMS',
         gasUsed: '0x2dc6c0',
+        calls: [],
       };
       const failingResultCall = {
         ...defaultResponseFields,
         type: 'CALL',
         error: 'CONTRACT_REVERT_EXECUTED',
         revertReason: 'Some revert message',
+        calls: [],
       };
 
       describe('Test transactions of type 0', async function () {