[Bug-fix] Translate JSONException to 400 instead of 500

Signed-off-by: Jialiang Liang <jiallian@amazon.com>

Author: RyanL1997

legacy/src/main/java/org/opensearch/sql/legacy/plugin/RestSqlAction.java

@@ -23,6 +23,7 @@
 import java.util.regex.Pattern;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.json.JSONException;
 import org.opensearch.OpenSearchException;
 import org.opensearch.common.inject.Injector;
 import org.opensearch.common.settings.Settings;
@@ -281,7 +282,8 @@ private static boolean isClientError(Exception e) {
         || e instanceof SqlAnalysisException
         || e instanceof SyntaxCheckException
         || e instanceof SemanticCheckException
-        || e instanceof ExpressionEvaluationException;
+        || e instanceof ExpressionEvaluationException
+        || e instanceof JSONException;
   }
 
   private void sendResponse(

plugin/src/main/java/org/opensearch/sql/plugin/rest/RestPPLQueryAction.java

@@ -37,6 +37,7 @@
 import org.opensearch.sql.plugin.transport.TransportPPLQueryRequest;
 import org.opensearch.sql.plugin.transport.TransportPPLQueryResponse;
 import org.opensearch.transport.client.node.NodeClient;
+import org.json.JSONException;
 
 public class RestPPLQueryAction extends BaseRestHandler {
   public static final String QUERY_API_ENDPOINT = "/_plugins/_ppl";
@@ -59,7 +60,8 @@ private static boolean isClientError(Exception e) {
         || e instanceof QueryEngineException
         || e instanceof SyntaxCheckException
         || e instanceof DataSourceClientException
-        || e instanceof IllegalAccessException;
+        || e instanceof IllegalAccessException
+        || e instanceof JSONException;
   }
 
   @Override