This is a bug, that makes sense to solve, when we develop the next stage of Termportal. Therefore it is turned into a sub-task, but actually has nothing to do with the new features, that have to be implemented for TRANSLATE-1405

To reproduce

• Import a TBX via filesystem termimport.
• Directly after the import call the same import URL again with the same import config, without copying the TBX again into the import folder (empty import folder)
• After the second import the termCollection is empty. Since no TBX has been found, nothing should happen, but an error should be triggered, that the configured TBX could not be found.