refactor(ReadHistoryQuery): update to not throw exception.

- update controller to throw NotFound if the list is empty

EnvelopeGenerator.Web/Controllers/Test/TestEnvelopeReceiverController.cs

@@ -27,7 +27,7 @@ public class TestEnvelopeReceiverController : ControllerBase
 
     [HttpGet]
     public async Task<IActionResult> Get([FromQuery] ReadEnvelopeReceiverQuery q, CancellationToken cancel) 
-        => Ok(await _mediator.Send(q, cancel).ThrowIfNull(Exceptions.NotFound));
+        => Ok(await _mediator.Send(q, cancel).ThrowIfEmpty(Exceptions.NotFound));
 
     [Obsolete("Use MediatR")]
     [HttpGet("verify-access-code/{envelope_receiver_id}")]