fix(baseapp): ensure finalize block response is not empty (#23879)

CHANGELOG.md

@@ -53,6 +53,7 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 ### Bug Fixes
 
 * (x/auth) [#23741](https://github.com/cosmos/cosmos-sdk/pull/23741) Support legacy global AccountNumber.
+* (baseapp) [#23879](https://github.com/cosmos/cosmos-sdk/pull/23879) Ensure finalize block response is not empty in the defer check of FinalizeBlock to avoid panic by nil pointer.
 * (types/query) [#23880](https://github.com/cosmos/cosmos-sdk/pull/23880) Fix NPE in query pagination.
 
 ### Removed

baseapp/abci.go

@@ -903,6 +903,9 @@ func (app *BaseApp) internalFinalizeBlock(ctx context.Context, req *abci.Finaliz
 // where they adhere to the sdk.Tx interface.
 func (app *BaseApp) FinalizeBlock(req *abci.FinalizeBlockRequest) (res *abci.FinalizeBlockResponse, err error) {
 	defer func() {
+		if res == nil {
+			return
+		}
 		// call the streaming service hooks with the FinalizeBlock messages
 		for _, streamingListener := range app.streamingManager.ABCIListeners {
 			if streamErr := streamingListener.ListenFinalizeBlock(app.finalizeBlockState.Context(), *req, *res); streamErr != nil {

baseapp/abci_test.go

@@ -2779,3 +2779,18 @@ func TestABCI_Proposal_FailReCheckTx(t *testing.T) {
 	require.NotEmpty(t, res.TxResults[0].Events)
 	require.True(t, res.TxResults[0].IsOK(), fmt.Sprintf("%v", res))
 }
+
+func TestFinalizeBlockDeferResponseHandle(t *testing.T) {
+	suite := NewBaseAppSuite(t, baseapp.SetHaltHeight(1))
+	suite.baseApp.SetStreamingManager(storetypes.StreamingManager{
+		ABCIListeners: []storetypes.ABCIListener{
+			&mockABCIListener{},
+		},
+	})
+
+	res, err := suite.baseApp.FinalizeBlock(&abci.FinalizeBlockRequest{
+		Height: 2,
+	})
+	require.Empty(t, res)
+	require.NotEmpty(t, err)
+}