Fix initial value of m_batching. In case no batching was required, it is set to to true, which makes the metric finalize ungracefully.

Author: Vincent Thiery

src/UDPSender.hpp

@@ -104,7 +104,7 @@ class UDPSender final
     // @{
 
     //! Shall the sender use batching?
-    bool m_batching;
+    bool m_batching{ false };
 
     //! The batching size
     uint64_t m_batchsize;