Explicitly initialize a member

Author: franzpoeschel

include/openPMD/snapshots/ContainerImpls.hpp

@@ -35,7 +35,7 @@ class StatefulSnapshotsContainer : public AbstractSnapshotsContainer
          * The iterator is resolved upon calling get() below.
          */
         std::variant<std::function<StatefulIterator *()>, StatefulIterator *>
-            m_bufferedIterator;
+            m_bufferedIterator = {};
     };
     Members members;