fixing test and enhancing error message

Signed-off-by: Amit Galitzky <amgalitz@amazon.com>

Author: amitgalitz

src/main/java/org/opensearch/flowframework/rest/RestCreateWorkflowAction.java

@@ -142,7 +142,8 @@ protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient cli
                         }
                     } catch (Exception ex) {
                         RestStatus status = ex instanceof IOException ? RestStatus.BAD_REQUEST : ExceptionsHelper.status(ex);
-                        String errorMessage = "failure parsing request body when a use case is given";
+                        String errorMessage =
+                            "failure parsing request body when a use case is given, make sure to provide a map with values that are either strings, arrays, or map of strings to strings";
                         logger.error(errorMessage, ex);
                         throw new FlowFrameworkException(errorMessage, status);
                     }

src/main/java/org/opensearch/flowframework/workflow/CreateIndexStep.java

@@ -93,10 +93,19 @@ public PlainActionFuture<WorkflowData> execute(
             byte[] byteArr = configurations.getBytes(StandardCharsets.UTF_8);
             BytesReference configurationsBytes = new BytesArray(byteArr);
             CreateIndexRequest createIndexRequest = new CreateIndexRequest(indexName);
-            if (!configurations.isEmpty()) {
-                Map<String, Object> sourceAsMap = XContentHelper.convertToMap(configurationsBytes, false, MediaTypeRegistry.JSON).v2();
-                sourceAsMap = prepareMappings(sourceAsMap);
-                createIndexRequest.source(sourceAsMap, LoggingDeprecationHandler.INSTANCE);
+
+            try {
+                if (!configurations.isEmpty()) {
+                    Map<String, Object> sourceAsMap = XContentHelper.convertToMap(configurationsBytes, false, MediaTypeRegistry.JSON).v2();
+                    sourceAsMap = prepareMappings(sourceAsMap);
+                    createIndexRequest.source(sourceAsMap, LoggingDeprecationHandler.INSTANCE);
+                }
+            } catch (Exception ex) {
+                String errorMessage = "Failed to create the index"
+                    + indexName
+                    + " due to incorrect mapping, make sure you aren't providing _doc in mapping";
+                logger.error(errorMessage, ex);
+                createIndexFuture.onFailure(new WorkflowStepException(errorMessage, RestStatus.BAD_REQUEST));
             }
 
             client.admin().indices().create(createIndexRequest, ActionListener.wrap(acknowledgedResponse -> {

src/test/java/org/opensearch/flowframework/workflow/CreateIndexStepTests.java

@@ -70,8 +70,7 @@ public void setUp() throws Exception {
         this.flowFrameworkIndicesHandler = mock(FlowFrameworkIndicesHandler.class);
         MockitoAnnotations.openMocks(this);
         String configurations =
-            "{\"settings\":{\"index\":{\"number_of_shards\":2,\"number_of_replicas\":1}},\"mappings\":{\"_doc\":{\"properties\":{\"age\":{\"type\":\"integer\"}}}},\"aliases\":{\"sample-alias1\":{}}}";
-
+            "{\"settings\":{\"index\":{\"number_of_shards\":2,\"number_of_replicas\":1}},\"mappings\":{\"properties\":{\"age\":{\"type\":\"integer\"}}},\"aliases\":{\"sample-alias1\":{}}}";
         inputData = new WorkflowData(
             Map.ofEntries(Map.entry(INDEX_NAME, "demo"), Map.entry(CONFIGURATIONS, configurations)),
             "test-id",