diff --git a/src/main/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessor.java b/src/main/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessor.java
index 3f434d3ce..55ee89bbd 100644
--- a/src/main/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessor.java
+++ b/src/main/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessor.java
@@ -177,14 +177,16 @@ private List<List<Float>> buildVectorFromResponse(MLOutput mlOutput) {
     private Map<String, ?> buildMapResultFromResponse(MLOutput mlOutput) {
         final ModelTensorOutput modelTensorOutput = (ModelTensorOutput) mlOutput;
         final List<ModelTensors> tensorOutputList = modelTensorOutput.getMlModelOutputs();
-        if (CollectionUtils.isEmpty(tensorOutputList)) {
-            log.error("No tensor output found!");
-            return null;
+        if (CollectionUtils.isEmpty(tensorOutputList) || CollectionUtils.isEmpty(tensorOutputList.get(0).getMlModelTensors())) {
+            throw new IllegalStateException(
+                "Empty model result produced. Expected 1 tensor output and 1 model tensor, but got [0]"
+            );
         }
         List<ModelTensor> tensorList = tensorOutputList.get(0).getMlModelTensors();
-        if (CollectionUtils.isEmpty(tensorList)) {
-            log.error("No tensor found!");
-            return null;
+        if (tensorList.size() != 1) {
+            throw new IllegalStateException(
+                "Unexpected number of map result produced. Expected 1 map result to be returned, but got [" + tensorList.size() + "]"
+            );
         }
         return tensorList.get(0).getDataAsMap();
     }
diff --git a/src/test/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessorTests.java b/src/test/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessorTests.java
index 813742878..d7c2cddcb 100644
--- a/src/test/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessorTests.java
+++ b/src/test/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessorTests.java
@@ -16,12 +16,14 @@
 import java.util.Map;
 
 import org.junit.Before;
+import org.mockito.ArgumentCaptor;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.Mockito;
 import org.mockito.MockitoAnnotations;
 import org.opensearch.cluster.node.DiscoveryNode;
 import org.opensearch.core.action.ActionListener;
+import org.opensearch.index.IndexNotFoundException;
 import org.opensearch.ml.client.MachineLearningNodeClient;
 import org.opensearch.ml.common.input.MLInput;
 import org.opensearch.ml.common.output.MLOutput;
@@ -177,7 +179,7 @@ public void test_inferenceSentencesWithMapResult_whenValidInput_thenSuccess() {
         Mockito.verifyNoMoreInteractions(resultListener);
     }
 
-    public void test_inferenceSentencesWithMapResult_whenTensorOutputListEmpty_thenReturnNull() {
+    public void test_inferenceSentencesWithMapResult_whenTensorOutputListEmpty_thenException() {
         final ActionListener<Map<String, ?>> resultListener = mock(ActionListener.class);
         final ModelTensorOutput modelTensorOutput = new ModelTensorOutput(Collections.emptyList());
         Mockito.doAnswer(invocation -> {
@@ -189,11 +191,13 @@ public void test_inferenceSentencesWithMapResult_whenTensorOutputListEmpty_thenR
 
         Mockito.verify(client)
             .predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
-        Mockito.verify(resultListener).onResponse(null);
+        ArgumentCaptor<Exception> argumentCaptor = ArgumentCaptor.forClass(IllegalStateException.class);
+        Mockito.verify(resultListener).onFailure(argumentCaptor.capture());
+        assertEquals("Empty model result produced. Expected 1 tensor output and 1 model tensor, but got [0]", argumentCaptor.getValue().getMessage());
         Mockito.verifyNoMoreInteractions(resultListener);
     }
 
-    public void test_inferenceSentencesWithMapResult_whenModelTensorListEmpty_thenReturnNull() {
+    public void test_inferenceSentencesWithMapResult_whenModelTensorListEmpty_thenException() {
         final ActionListener<Map<String, ?>> resultListener = mock(ActionListener.class);
         final List<ModelTensors> tensorsList = new ArrayList<>();
         final List<ModelTensor> mlModelTensorList = new ArrayList<>();
@@ -208,7 +212,41 @@ public void test_inferenceSentencesWithMapResult_whenModelTensorListEmpty_thenRe
 
         Mockito.verify(client)
             .predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
-        Mockito.verify(resultListener).onResponse(null);
+        ArgumentCaptor<Exception> argumentCaptor = ArgumentCaptor.forClass(IllegalStateException.class);
+        Mockito.verify(resultListener).onFailure(argumentCaptor.capture());
+        assertEquals("Empty model result produced. Expected 1 tensor output and 1 model tensor, but got [0]", argumentCaptor.getValue().getMessage());
+        Mockito.verifyNoMoreInteractions(resultListener);
+    }
+
+    public void test_inferenceSentencesWithMapResult_whenModelTensorListSizeBiggerThan1_thenException() {
+        final ActionListener<Map<String, ?>> resultListener = mock(ActionListener.class);
+        final List<ModelTensors> tensorsList = new ArrayList<>();
+        final List<ModelTensor> mlModelTensorList = new ArrayList<>();
+        final ModelTensor tensor = new ModelTensor(
+            "response",
+            null,
+            null,
+            null,
+            null,
+            null,
+           Map.of("key", "value")
+        );
+        mlModelTensorList.add(tensor);
+        mlModelTensorList.add(tensor);
+        tensorsList.add(new ModelTensors(mlModelTensorList));
+        final ModelTensorOutput modelTensorOutput = new ModelTensorOutput(tensorsList);
+        Mockito.doAnswer(invocation -> {
+            final ActionListener<MLOutput> actionListener = invocation.getArgument(2);
+            actionListener.onResponse(modelTensorOutput);
+            return null;
+        }).when(client).predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
+        accessor.inferenceSentencesWithMapResult(TestCommonConstants.MODEL_ID, TestCommonConstants.SENTENCES_LIST, resultListener);
+
+        Mockito.verify(client)
+            .predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
+        ArgumentCaptor<Exception> argumentCaptor = ArgumentCaptor.forClass(IllegalStateException.class);
+        Mockito.verify(resultListener).onFailure(argumentCaptor.capture());
+        assertEquals("Unexpected number of map result produced. Expected 1 map result to be returned, but got [2]", argumentCaptor.getValue().getMessage());
         Mockito.verifyNoMoreInteractions(resultListener);
     }