title: Error in sample / template Azure Bot Framework solution 'EchoBot' without having modified any code
body: <p>I have downloaded the Azure 'EchoBot' sample from Azure, using Azure Portal > Create Resource > Web App Bot > V4 Framework > Echo Bot. </p>
  
  <p>I downloaded the resulting scaffolding code, and it seems to have an error already in the sample? I can't fix it myself, because I don't really understand the structure of the code yet. This was to be my learning exercise. It appears to be an error in the dependency injection during startup? I have updated all nuget packages and confirmed that other examples/samples on the net have this same code? (Replacing 'EchoBot' with the name of their solution). Can anyone assist? I can't even build and run the sample with this issue/error. </p>
  
  <p><a href="https://i.stack.imgur.com/cuvEv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cuvEv.png" alt="enter image description here"></a></p>