SignIn issue

Followed all the steps to create app registration, permissions, bot service etc etc but when I add this in code:

` [Message]
public async Task OnEveryMessage(IContext context, [Context] IContext.Client client)
{
if (!context.IsSignedIn)
{
await client.SignIn();
}
}`
I obtain a Stack Overflow exception with a VERY long stack trace :), a snippet is reported at the end of the issue, should be enough to get the recursion problem.

If instead of client.SignIn() I use await context.SignIn(); I obtain this exception:
`System.InvalidCastException: 'Unable to cast object of type 'Microsoft.Teams.Apps.Context`1[Microsoft.Teams.Api.Activities.MessageActivity]' to type 'Microsoft.Teams.Apps.IContext`1[Microsoft.Teams.Api.Activities.IActivity]'.'`

Examples lacks on documenting this for C#, actually in the dotnet docs there are typescript snippets.
Thanks!

### Stack Trace snippet
at Microsoft.Teams.Api.Activities.Invokes.SignInActivity+JsonConverter.Read(System.Text.Json.Utf8JsonReader ByRef, System.Type, System.Text.Json.JsonSerializerOptions)
at System.Text.Json.Serialization.JsonConverter`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].TryRead(System.Text.Json.Utf8JsonReader ByRef, System.Type, System.Text.Json.JsonSerializerOptions, System.Text.Json.ReadStack ByRef, System.__Canon ByRef, Boolean ByRef)
at System.Text.Json.Serialization.JsonConverter`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].ReadCore(System.Text.Json.Utf8JsonReader ByRef, System.__Canon ByRef, System.Text.Json.JsonSerializerOptions, System.Text.Json.ReadStack ByRef)
at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].Deserialize(System.Text.Json.Utf8JsonReader ByRef, System.Text.Json.ReadStack ByRef)
at System.Text.Json.JsonSerializer.ReadFromSpan[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.ReadOnlySpan`1, System.Text.Json.Serialization.Metadata.JsonTypeInfo`1, System.Nullable`1)
at System.Text.Json.JsonSerializer.ReadFromSpan[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.ReadOnlySpan`1, System.Text.Json.Serialization.Metadata.JsonTypeInfo`1)
at System.Text.Json.JsonSerializer.Deserialize[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.String, System.Text.Json.JsonSerializerOptions)
at Microsoft.Teams.Api.Activities.InvokeActivity+JsonConverter.Read(System.Text.Json.Utf8JsonReader ByRef, System.Type, System.Text.Json.JsonSerializerOptions)
at System.Text.Json.Serialization.JsonConverter`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].TryRead(System.Text.Json.Utf8JsonReader ByRef, System.Type, System.Text.Json.JsonSerializerOptions, System.Text.Json.ReadStack ByRef, System.__Canon ByRef, Boolean ByRef)
at System.Text.Json.Serialization.JsonConverter`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].ReadCore(System.Text.Json.Utf8JsonReader ByRef, System.__Canon ByRef, System.Text.Json.JsonSerializerOptions, System.Text.Json.ReadStack ByRef)
at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].Deserialize(System.Text.Json.Utf8JsonReader ByRef, System.Text.Json.ReadStack ByRef)
at System.Text.Json.JsonSerializer.ReadFromSpan[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.ReadOnlySpan`1, System.Text.Json.Serialization.Metadata.JsonTypeInfo`1, System.Nullable`1)
at System.Text.Json.JsonSerializer.ReadFromSpan[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.ReadOnlySpan`1, System.Text.Json.Serialization.Metadata.JsonTypeInfo`1)
at System.Text.Json.JsonSerializer.Deserialize[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.String, System.Text.Json.JsonSerializerOptions)
at Microsoft.Teams.Api.Activities.Activity+JsonConverter.Read(System.Text.Json.Utf8JsonReader ByRef, System.Type, System.Text.Json.JsonSerializerOptions)
at System.Text.Json.Serialization.JsonConverter`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].TryRead(System.Text.Json.Utf8JsonReader ByRef, System.Type, System.Text.Json.JsonSerializerOptions, System.Text.Json.ReadStack ByRef, System.__Canon ByRef, Boolean ByRef)
at System.Text.Json.Serialization.JsonConverter`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].ReadCore(System.Text.Json.Utf8JsonReader ByRef, System.__Canon ByRef, System.Text.Json.JsonSerializerOptions, System.Text.Json.ReadStack ByRef)
at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].ContinueDeserialize(System.Text.Json.Serialization.ReadBufferState ByRef, System.Text.Json.JsonReaderState ByRef, System.Text.Json.ReadStack ByRef, System.__Canon ByRef)
at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1+d__1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[[System.Text.Json.Serialization.Metadata.JsonTypeInfo`1+d__1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]], System.Text.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51]](d__1 ByRef)
at System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].Start[[System.Text.Json.Serialization.Metadata.JsonTypeInfo`1+d__1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]], System.Text.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51]](d__1 ByRef)
at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].DeserializeAsync(System.IO.Stream, System.Threading.CancellationToken)
at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1+d__6[[System.__Canon, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()

Start with the OnEveryMessage snippet and the SignIn and context.SignIn calls described in the issue, then reproduce both reported exceptions using the provided stack-trace snippet. Trace the sign-in and JSON conversion path to determine the supported C# usage. Done means the sign-in flow no longer causes either exception and the working C# usage is documented.

Written by the indexing model from the issue text.