ensure that we have an msrunreader, and ensure that this resource is freed after operation

src/core/msrun.cpp

@@ -270,7 +270,9 @@ MsRun::checkMsRunStatistics()
     {
       try
         {
+
           MsRunStatisticsHandler stats;
+          _msrun_reader_sp = getMsRunReaderSPtr();
           _msrun_reader_sp.get()->readSpectrumCollection(stats);
 
           setMsRunStatistics(MsRunStatistics::total_spectra,
@@ -293,6 +295,7 @@ MsRun::checkMsRunStatistics()
           // no file found, no statistics
         }
     }
+  freeMsRunReaderSp();
 }
 
 void
@@ -303,6 +306,7 @@ MsRun::checkMsRunStatistics(MsRunStatisticsHandler *currentHandler)
     {
       try
         {
+          _msrun_reader_sp = getMsRunReaderSPtr();
           _msrun_reader_sp.get()->readSpectrumCollection(*currentHandler);
           if(currentHandler->shouldStop())
             { // statistics handler was stopped : don't use collected statistics
@@ -334,6 +338,7 @@ MsRun::checkMsRunStatistics(MsRunStatisticsHandler *currentHandler)
           // no file found, no statistics
         }
     }
+  freeMsRunReaderSp();
 }
 
 void