Fix crash bug in graphing window when trying to edit graphs that don't

hvae a corresponding signal entry in a DBC file

re/newgraphdialog.cpp

@@ -227,6 +227,8 @@ void NewGraphDialog::setParams(GraphParams &params)
 
     loadNodes();
 
+    if (assocSignal)
+    {
         auto msg = assocSignal->parentMessage;
         auto node = msg->sender;
 
@@ -274,6 +276,7 @@ void NewGraphDialog::setParams(GraphParams &params)
                 qDebug() << "Matching plot params to Signal: " << sigFound;
             }
         }
+    }
     //ui->cbNodes->model()->