I created simple node.js application (source code from here https://azure.microsoft.com/en-us/blog/visual-studio-code-and-azure-app-service-a-perfect-fit/)
var h
It simply means that when you debug the file the app.js file simply doesn't exist and when you perform debugging it shows the error. Here it my way to fix the problem : simply replace the value of program
"${workspaceRoot}/app.js"
by
"${workspaceFolder}/${fileBasenameNoExtension}.js"
I hope this will solve all of your problems.