SSDT2012 (11.1.20905.0) apparently is not identified as a supported version of Visual Studio.
From the log:
...
- Found installed product - Microsoft Visual Studio 2012 Shell (Integrated)
- Found installed product - Global Location
- Found installed product - ssms
-
VSIXInstaller.NoApplicableSKUsException: This extension is not installable on any currently installed products.
at VSIXInstaller.App.InitializeInstall()
at System.Threading.Tasks.Task.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
Kind regards