Stick to StatusCode::INTERNAL when there's no service

response on a StreamedUnary

include/grpc++/impl/codegen/method_handler_impl.h

@@ -194,8 +194,8 @@ class TemplatedBidiStreamingHandler : public MethodHandler {
       if (write_needed_ && status.ok()) {
         // If we needed a write but never did one, we need to mark the
         // status as a fail
-        status = Status(IMPROPER_IMPLEMENTATION,
-                        "Service did not provide response message");
+        status = Status(StatusCode::INTERNAL,
+			"Service did not provide response message");
       }
     }
     ops.ServerSendStatus(param.server_context->trailing_metadata_, status);

include/grpc++/impl/codegen/status_code_enum.h

@@ -143,11 +143,6 @@ enum StatusCode {
   /// Unrecoverable data loss or corruption.
   DATA_LOSS = 15,
 
-  // Service was improperly implemented, violated a gRPC API requirement
-  // Not quite the same as unimplemented since it could just be that the API
-  // requirement was violated in this particular circumstance
-  IMPROPER_IMPLEMENTATION = 16,
-
   /// Force users to include a default branch:
   DO_NOT_USE = -1
 };