Use exit() instead of quit() to be able to add a returnCode in case of failure.

worker.h

@@ -122,6 +122,7 @@ class Worker : public QObject {
     QStringList m_filesToUpdate;
     bool m_updateProcessRunning;
     int m_displayIndex;
+    int m_returnCode;
 
     bool executeOpkgCommand(QString opkgCommand);
     QString getOsVersion() const;
@@ -156,6 +157,7 @@ public:
     IsmasClient const &getIsmasClient() const { return m_ismasClient; }
 
     bool updateProcessRunning() const { return m_updateProcessRunning; }
+    bool returnCode() const { return m_returnCode; }
 
     int machineNr() const { return m_machineNr; }
     int customerNr() const { return m_customerNr; }