Download of empty OpenTM2-TM leads to error in translate5

If you download an empty openTM2 TM (newly created), the following error occurs. Instead the user should see a message, that the TM is empty and can not be downloaded.

ZfExtended_Log on xxx.translate5.net: exception 'ZfExtended_BadGateway' with message 'Die angefragte OpenTM2 Instanz meldete folgenden Fehler:
Array
(
[0] => stdClass Object
(
[type] => HTTP
[error] => 500
[url] => http://livewin.translate5.net:1984/otmmemoryservice/xxx-ID15-yyy+EN-BG/
[method] => GET
)

)
' in /webs/xxx.translate5.net/application/modules/editor/Services/OpenTM2/Connector.php:487
Stack trace:
#0 /webs/xxx.translate5.net/application/modules/editor/Services/OpenTM2/Connector.php(178): editor_Services_OpenTM2_Connector->throwBadGateway()
#1 [internal function]: editor_Services_OpenTM2_Connector->getTm('application/xml')
#2 /webs/xxx.translate5.net/application/modules/editor/Services/Connector.php(144): call_user_func_array(Array, Array)
#3 /webs/xxx.translate5.net/application/modules/editor/Controllers/LanguageresourceinstanceController.php(422): editor_Services_Connector->__call('getTm', Array)
#4 /webs/xxx.translate5.net/application/modules/editor/Controllers/LanguageresourceinstanceController.php(422): editor_Services_Connector->getTm('application/xml')
#5 /webs/mittagqi_meta/other/zend/ZendFramework-1.12.20-minimal/library/Zend/Controller/Action.php(516): editor_LanguageresourceinstanceController->downloadAction()
#6 /webs/xxx.translate5.net/library/ZfExtended/Controllers/AAARestController.php(287): Zend_Controller_Action->dispatch('downloadAction')
#7 /webs/mittagqi_meta/other/zend/ZendFramework-1.12.20-minimal/library/Zend/Controller/Dispatcher/Standard.php(308): ZfExtended_RestController->dispatch('downloadAction')
#8 /webs/mittagqi_meta/other/zend/ZendFramework-1.12.20-minimal/library/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(REST_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#9 /webs/mittagqi_meta/other/zend/ZendFramework-1.12.20-minimal/library/Zend/Application/Bootstrap/Bootstrap.php(105): Zend_Controller_Front->dispatch()
#10 /webs/mittagqi_meta/other/zend/ZendFramework-1.12.20-minimal/library/Zend/Application.php(384): Zend_Application_Bootstrap_Bootstrap->run()
#11 /webs/xxx.translate5.net/library/ZfExtended/BaseIndex.php(167): Zend_Application->run()
#12 /webs/xxx.translate5.net/public/index.php(35): ZfExtended_BaseIndex->startApplication()
#13 {main}

Additional error data: Array
(
[0] => stdClass Object
(
[type] => HTTP
[error] => 500
[url] => http://livewin.translate5.net:1984/otmmemoryservice/xxx-ID15-yyy+EN-BG/
[method] => GET
)

)

Aufgerufene URL inkl. ggf. vorhandener POST-Parameter als get-Parameter:

/editor/languageresourceinstance/download/id/15/type/download.tmx/format/xml