preprocessor fix for ratio calculations

adapter-cqld4/src/main/java/io/nosqlbench/converters/cql/exporters/CqlWorkloadExporter.java

@@ -48,6 +48,8 @@ import java.util.stream.Collectors;
  * Thus if you feed it one create statement at a time, it will yield a workload with just that,
  * and if you feed it an elaborate schema, it will generate a workload inclusive of all
  * provided elements.
+ *
+ * @see <a href="https://cassandra.apache.org/doc/trunk/cassandra/cql/index.html">Apache Cassandra CQL Docs</a>
  */
 public class CqlWorkloadExporter {
     private final static Logger logger = LogManager.getLogger(CqlWorkloadExporter.class);

adapter-cqld4/src/main/java/io/nosqlbench/converters/cql/exporters/transformers/RatioCalculator.java

@@ -25,6 +25,9 @@ public class RatioCalculator implements Function<CqlModel,CqlModel> {
 
     @Override
     public CqlModel apply(CqlModel model) {
+        if (!model.hasStats()) {
+            return model;
+        }
         double totalReads = 0.0d;
         double totalWrites = 0.0d;
         double totalSpace = 0.0d;