make sure that the 'selected' object is present.

src/classes/PMusrCanvas.cpp

@@ -941,9 +941,10 @@ void PMusrCanvas::HandleCmdKey(Int_t event, Int_t x, Int_t y, TObject *selected)
 
   // this is a workaround which should prevent that the key event is executed if
   // a text/latex is written into the canvas.
+  if (selected) {
     if (!strcmp(selected->GetTitle(), "dataTheoryPad"))
       return;
-
+  }
 
   if (fBatchMode) {
     if (fStartWithAvg) { // this is needed to get the averaging in the batch mode