createRandomModiciation field now is returned as false if it is null

Author: ic0ns

src/main/java/de/rub/nds/modifiablevariable/ModifiableVariable.java

@@ -156,6 +156,9 @@ public boolean containsAssertion() {
     }
 
     public Boolean isCreateRandomModification() {
+        if (createRandomModification == null) {
+            return false;
+        }
         return createRandomModification;
     }
 }