解决选择设备时点击取消，弹窗提示异常的问题

app/scanner2/device_user.cpp

@@ -262,7 +262,7 @@ HGResult DeviceUser::Open()
     {
         HGChar errInfo[256];
         HGResult ret = HGSane_OpenSelectedDevice(m_source, m_wnd, &m_saneDev, errInfo, 256);
-        if (HGBASE_ERR_OK != ret)
+        if (HGBASE_ERR_OK != ret && strlen(errInfo) != 0)
         {
             QMessageBox::information(m_wnd, tr("Prompt"), errInfo);
         }

modules/sane_user/HGSaneImpl.cpp

@@ -558,6 +558,7 @@ HGResult HGSaneSourceImpl::OpenSelectedDevice(HGWindow parent, class HGSaneDevic
     int id = choose_scanner(devs);
     if (-1 == id)
     {
+        memset(errInfo, 0, sizeof(errInfo));
         return HGSANE_ERR_FAIL;
     }