title: Method may only be called on a Type for which Type.IsGenericParameter is true after upgrading ServiceStack app to NetCore 3
body: <p>After upgrading a ServiceStack based api app from NetCore 2.x to NetCore 3.0, my Angular app is receiving errors from the api when the server tries to return the response from what I can see.</p>
  
  <pre><code>ServiceStack.Host.Handlers.HttpAsyncTaskHandler: 2019-10-25 21:50:26,248 [22] DEBUG ServiceStack.Host.Handlers.HttpAsyncTaskHandler - CreateRequestAsync/requestParams:
  ServiceStack.Host.Handlers.HttpAsyncTaskHandler: 2019-10-25 21:50:26,249 [12] DEBUG ServiceStack.Host.Handlers.HttpAsyncTaskHandler - CreateRequestAsync/requestParams:
  ServiceStack.ServiceStackHost: 2019-10-25 21:50:26,276 [4] ERROR ServiceStack.ServiceStackHost - ServiceBase&lt;TRequest&gt;::Service Exception
  System.InvalidOperationException: Method may only be called on a Type for which Type.IsGenericParameter is true.
     at System.RuntimeType.get_DeclaringMethod()
  </code></pre>
  
  <p>Any tips as to what this issue is?</p>