Hii i get this error and i don’ t really know how to solve it:gather_out_cpu(): Expected dtype int64 for index
and this is my code     def learn(self, batch_state, batch_next_state, batch_reward, batch_action):         outputs = self.model(batch_state).gather(1, batch_action.unsqueeze(1)).squeeze(1)         next_outputs = self.model(batch_next_state).detach().max(1)[0]         target = self.gamma * next_outputs + batch_reward         td_loss = F.smooth_l1_loss(outputs, target)         self.optimizer.zero_grad()         td_loss.backward(retain_variables = True)         self.optimizer.step()