Add a error case for accessing different levels of nested objects in scripts

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

integ-test/src/test/java/org/opensearch/sql/calcite/remote/CalciteWhereCommandIT.java

@@ -11,6 +11,7 @@
 import static org.opensearch.sql.util.MatcherUtils.rows;
 import static org.opensearch.sql.util.MatcherUtils.schema;
 import static org.opensearch.sql.util.MatcherUtils.verifyDataRows;
+import static org.opensearch.sql.util.MatcherUtils.verifyErrorMessageContains;
 import static org.opensearch.sql.util.MatcherUtils.verifySchema;
 
 import java.io.IOException;
@@ -81,6 +82,8 @@ public void testFilterOnNestedFields() throws IOException {
 
   @Test
   public void testFilterOnMultipleCascadedNestedFields() throws IOException {
+    // SQL's static type system does not allow returning list[int] in place of int
+    enabledOnlyWhenPushdownIsEnabled();
     JSONObject result =
         executeQuery(
             String.format(
@@ -119,4 +122,22 @@ public void testFilterOnMultipleCascadedNestedFields() throws IOException {
                             "comment",
                             "Too slow in places"))))));
   }
+
+  @Test
+  public void testScriptFilterOnDifferentNestedHierarchyShouldThrow() throws IOException {
+    enabledOnlyWhenPushdownIsEnabled();
+    Throwable t =
+        assertThrows(
+            Exception.class,
+            () ->
+                executeQuery(
+                    String.format(
+                        "source=%s | where author.books.reviews.rating + length(author.books.title)"
+                            + " > 10",
+                        TEST_INDEX_CASCADED_NESTED)));
+    verifyErrorMessageContains(
+        t,
+        "Accessing multiple nested fields under different hierarchies in script is not supported:"
+            + " [author.books.reviews, author.books]");
+  }
 }

opensearch/src/main/java/org/opensearch/sql/opensearch/request/PredicateAnalyzer.java

@@ -1523,11 +1523,11 @@ public QueryBuilder builder() {
               .distinct()
               .collect(Collectors.toUnmodifiableList());
       if (nestedPaths.size() > 1) {
-        throw new UnsupportedOperationException(
+        throw new UnsupportedScriptException(
             String.format(
                 Locale.ROOT,
-                "Accessing multiple nested fields under different hierarchies is not supported:"
-                    + " %s",
+                "Accessing multiple nested fields under different hierarchies in script is not"
+                    + " supported: %s",
                 nestedPaths));
       }
       if (!nestedPaths.isEmpty()) {