refactor: check if null in PreparedStatement (#1795)

Author: vighnesh-kadam

java/openmldb-jdbc/src/main/java/com/_4paradigm/openmldb/jdbc/PreparedStatement.java

@@ -272,13 +272,12 @@ protected void dataBuild() throws SQLException {
                 columnTypes.AddColumnType(types.get(i + 1));
             }
             this.currentRow = SQLRequestRow.CreateSQLRequestRowFromColumnTypes(columnTypes);
-            // TODO(hw): check if null
+            if (this.currentRow == null) {
+        	throw new SQLException("fail to create sql request row from column types");
+            }
             this.currentSchema = this.currentRow.GetSchema();
             this.orgTypes = this.types;
         }
-        if (this.currentRow == null) {
-            throw new SQLException("fail to build data with null row");
-        }
         if (this.currentSchema == null) {
             throw new SQLException("fail to build data with null schema");
         }