Set Variable.m_Value at opening for single value variables

source/adios2/helper/adiosXML.cpp

@@ -164,6 +164,13 @@ void InitXML(const std::string configXML, MPI_Comm mpiComm,
 
     fileContents = BroadcastValue(fileContents, mpiComm);
 
+    if (debugMode && fileContents.empty())
+    {
+        throw std::invalid_argument("ERROR: config xml file " + configXML +
+                                    " is either empty or file couldn't be "
+                                    "found, in call to ADIOS constructor\n");
+    }
+
     pugi::xml_document doc;
     auto parse_result = doc.load_buffer_inplace(
         const_cast<char *>(fileContents.data()), fileContents.size());

source/adios2/toolkit/format/bp3/BP3Deserializer.tcc

@@ -123,6 +123,7 @@ BP3Deserializer::DefineVariableInIO(const ElementIndexHeader &header, IO &io,
     {
         std::lock_guard<std::mutex> lock(m_Mutex);
         variable = &io.DefineVariable<T>(variableName);
+        variable->m_Value = characteristics.Statistics.Value;
         variable->m_Min = characteristics.Statistics.Value;
         variable->m_Max = characteristics.Statistics.Value;
     }