Invalid binary -> FAIL.txt "The transfer timed out."

When drag and dropping a nRF52 binary the first bytes are validated in to be valid.
https://github.com/ARMmbed/DAPLink/blob/master/source/daplink/validation.c#L55

The problem is if they are not valid, the FAIL.txt will contain
"The transfer timed out."
There seems to be an
else if( NNN){}
missing here
https://github.com/ARMmbed/DAPLink/blob/master/source/daplink/drag-n-drop/vfs_manager.c#L798

Read source/daplink/validation.c around line 55 and source/daplink/drag-n-drop/vfs_manager.c around line 798, then trace how invalid nRF52 binary bytes reach the transfer result. Confirm the failure path reports an invalid binary in FAIL.txt rather than "The transfer timed out.".

Written by the indexing model from the issue text.