Fix calling GUI methods from script thread

loadrunable.cpp

@@ -615,7 +615,7 @@ void ConvertRunable::run()
 
     if(rawimage)
     {
-        if(m_format == "XISF")
+        if(m_format == "xisf")
         {
             try
             {
@@ -674,9 +674,10 @@ void ConvertRunable::run()
             {
                 qDebug() << "Failed to save XISF image" <<  err.what();
             }
+            return;
         }
 
-        if(m_format == "FITS")
+        if(m_format == "fits")
         {
             int status = 0;
             fitsfile *fw;
@@ -691,9 +692,10 @@ void ConvertRunable::run()
             }
             writeFITSImage(fw, rawimage, imageinfo);
             fits_close_file(fw, &status);
+            return;
         }
 
-        if(m_format == "QIMAGE")
+        // if nothing else try QImage
         {
             QImage::Format format = QImage::Format_Invalid;
             int width = rawimage->widthBytes();