message: Handle the case that CancellationManager is null in eager mode
diff: @@ -601,9 +601,11 @@ LoopCondOp::~LoopCondOp() = default;
  void LoopCondOp::Compute(OpKernelContext* context) {
  CancellationManager* cm = context->cancellation_manager();
  + if (cm != nullptr) {
  bool already_cancelled = cm->IsCancelled();
  OP_REQUIRES(context, !already_cancelled,
  errors::Cancelled("Loop execution was cancelled."));
  + }
  context->set_output(0, context->input(0));
  }
  