Removed default constructor, copy constructor and assignment operator for CheckHandler.
diff --git a/src/check.h b/src/check.h
index 2b04cd2..d2c1fda 100644
--- a/src/check.h
+++ b/src/check.h
@@ -30,6 +30,9 @@
       std::abort();
   }
 
+  CheckHandler & operator=(const CheckHandler&) = delete;

+  CheckHandler(const CheckHandler&) = delete;

+  CheckHandler() = delete;
 private:
   std::ostream& log_;
 };