vscode-csharp: launch.json The property 'program' is invalid for .dll file

1. Setup: I have installed Visual Studio code on My Ubuntu and installed .NET Core and Mono.

2. Intial Configuration: I created a simple demo app running notnet restore and dotnet run. This simply works fine and display “Hello World!” on terminal.

3. Extension: To debug this, I installed extension of OmniSharp. and then using “Debugger” option of Visual Studio Code, I added launch.json & task.json.

4. launch.json (Only showing configuration section):

....
"configurations": [
    {
        "name": ".NET Core Launch (console)",
        "type": "coreclr",
        "request": "launch",
        "preLaunchTask": "build",
        "program": "${workspaceRoot}/bin/Debug/netstandardapp1.5/hwAppCore2.dll",
        "args": [],
        "cwd": "${workspaceRoot}",
        "stopAtEntry": false
    }    
....

5. Now, when running from terminal it works fine, however when try to debug using option .NET Core Launch (console) I am getting following error:

“launch: The property ‘program’ is invalid. ‘/home/ak/dotnet_core/hwAppCore2/bin/Debug/netstandardapp1.5/hwAppCore2.dll’ is a library (.dll), not a program.”

I also followed one of Channel 9 demo, and there also I can see hwapp.dll configured for program property of launch.json

I am not sure, am I missing anything to configure?