I cannot reproduce this. Using your example, if "toaster" doesn't exist, here is the expected result:
PS C:\Software\Toolkit\1.2.0> Connect-NaController "toaster"
Connect-NaController : No such host is known
At line:1 char:21
+ Connect-NaController <<<< "toaster"
+ CategoryInfo : NotSpecified: (:) [Connect-NaController], SocketException
+ FullyQualifiedErrorId : System.Net.Sockets.SocketException,DataONTAP.PowerShell.SDK.ConnectNaController
-- or possibly --
PS C:\Software\Toolkit\1.2.0> Connect-NaController "toaster"
Connect-NaController : The requested name is valid, but no data of the requested type was found
At line:1 char:21
+ Connect-NaController <<<< "toaster2"
+ CategoryInfo : NotSpecified: (:) [Connect-NaController], SocketException
+ FullyQualifiedErrorId : System.Net.Sockets.SocketException,DataONTAP.PowerShell.SDK.ConnectNaController
If "toaster" isn't a Data ONTAP controller, you might see:
PS C:\Software\Toolkit\1.2.0> Connect-NaController "toaster"
Connect-NaController : RPC Error - The RPC server is unavailable.
At line:1 char:21
+ Connect-NaController <<<< "toaster"
+ CategoryInfo : InvalidResult: (NetApp.Ontapi.Filer.NaController:NaController) [Connect-NaController], EAPITRANSMISSION
+ FullyQualifiedErrorId : RpcConnectionFailed,DataONTAP.PowerShell.SDK.ConnectNaController
The DLL in your error message is unrelated to the Toolkit, so I suspect an issue with your local environment. There was a similar report recently that turned out to be something other than a Toolkit issue. A failure in Connect-NaController doesn't always throw a terminating error, so it's a good idea to either check for a null result or specify "-ErrorAction Stop" if that's what you want.