KeyError: 'eval_loss' (LLaMA finetuning)
### System Info

- `transformers` version: 4.28.1
- Platform: Linux-5.15.90.1-microsoft-standard-WSL2-x86_64-with-glibc2.35
- Python version: 3.10.6
- Huggingface_hub version: 0.13.3
- Safetensors version: 0.3.0
- PyTorch version (GPU?): 2.0.0+cu117 (True)
- Jax version: not installed
- JaxLib version: not installed
- Using GPU in script?: Yes RTX 3090
- Using distributed or parallel set-up in script?: No

I'm running into this issue whenever I use a DatasetDict as the evaluation dataset

```
traceback (most recent call last):
  File "/mnt/e/alpaca-lora/finetune.py", line 304, in <module>
    fire.Fire(train)
  File "/home/coen/.local/lib/python3.10/site-packages/fire/core.py", line 141, in Fire
    component_trace = _Fire(component, args, parsed_flag_args, context, name)
  File "/home/coen/.local/lib/python3.10/site-packages/fire/core.py", line 475, in _Fire
    component, remaining_args = _CallAndUpdateTrace(
  File "/home/coen/.local/lib/python3.10/site-packages/fire/core.py", line 691, in _CallAndUpdateTrace
    component = fn(*varargs, **kwargs)
  File "/mnt/e/alpaca-lora/finetune.py", line 294, in train
    trainer.train(resume_from_checkpoint=resume_from_checkpoint)
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 1662, in train
    return inner_training_loop(
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 2006, in _inner_training_loop
    self._maybe_log_save_evaluate(tr_loss, model, trial, epoch, ignore_keys_for_eval)
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 2291, in _maybe_log_save_evaluate
    self._save_checkpoint(model, trial, metrics=metrics)
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 2394, in _save_checkpoint
    metric_value = metrics[metric_to_check]
KeyError: 'eval_loss'
Traceback (most recent call last):
  File "/mnt/e/alpaca-lora/finetune.py", line 304, in <module>
    fire.Fire(train)
  File "/home/coen/.local/lib/python3.10/site-packages/fire/core.py", line 141, in Fire
    component_trace = _Fire(component, args, parsed_flag_args, context, name)
  File "/home/coen/.local/lib/python3.10/site-packages/fire/core.py", line 475, in _Fire
    component, remaining_args = _CallAndUpdateTrace(
  File "/home/coen/.local/lib/python3.10/site-packages/fire/core.py", line 691, in _CallAndUpdateTrace
    component = fn(*varargs, **kwargs)
  File "/mnt/e/alpaca-lora/finetune.py", line 294, in train
    trainer.train(resume_from_checkpoint=resume_from_checkpoint)
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 1662, in train
    return inner_training_loop(
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 2006, in _inner_training_loop
    self._maybe_log_save_evaluate(tr_loss, model, trial, epoch, ignore_keys_for_eval)
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 2291, in _maybe_log_save_evaluate
    self._save_checkpoint(model, trial, metrics=metrics)
  File "/home/coen/.local/lib/python3.10/site-packages/transformers/trainer.py", line 2394, in _save_checkpoint
    metric_value = metrics[metric_to_check]
KeyError: 'eval_loss'
```

### Who can help?

@sgugger

### Information

- [ ] The official example scripts
- [x] My own modified scripts

### Tasks

- [X] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction

1. Download [Alpaca-Lora](https://github.com/tloen/alpaca-lora) from the repository
2. Modify the code

```
    if val_data_path is not None:
        train_data = (
            # data.select(range(10)).shuffle().map(generate_and_tokenize_prompt)
            data.shuffle().map(generate_and_tokenize_prompt)
        )

        val_data: DatasetDict = load_from_disk(val_data_path)

        val_data = (
            val_data.map(generate_and_tokenize_prompt)
        )
    elif val_set_size > 0:
        train_val = data.train_test_split(
            test_size=val_set_size, shuffle=True, seed=42
        )
        train_data = (
            train_val["train"].shuffle().map(generate_and_tokenize_prompt)
        )
        val_data: Dataset = (
            train_val["test"].shuffle().map(generate_and_tokenize_prompt)
        )
    else:
        train_data = data["train"].shuffle().map(generate_and_tokenize_prompt)
        val_data: None = None

    if not ddp and torch.cuda.device_count() > 1:
        # keeps Trainer from trying its own DataParallelism when more than 1 gpu is available
        model.is_parallelizable = True
        model.model_parallel = True

    # def compute_metrics(eval_preds):
    #     metric = evaluate.load("glue", "mrpc")
    #     logits, labels = eval_preds
    #     predictions = np.argmax(logits, axis=-1)
    #     return metric.compute(predictions=predictions, references=labels)

    trainer = transformers.Trainer(
        model=model,
        train_dataset=train_data,
        eval_dataset=val_data,
        args=transformers.TrainingArguments(
            per_device_train_batch_size=micro_batch_size,
            gradient_accumulation_steps=gradient_accumulation_steps,
            warmup_steps=100,
            num_train_epochs=num_epochs,
            learning_rate=learning_rate,
            fp16=True,
            logging_steps=10,
            optim="adamw_torch",
            evaluation_strategy="steps" if val_set_size > 0 else "no",
            save_strategy="steps",
            eval_steps=200 if val_set_size > 0 else None,
            save_steps=200,
            output_dir=output_dir,
            save_total_limit=3,
            load_best_model_at_end=True if val_set_size > 0 else False,
            ddp_find_unused_parameters=False if ddp else None,
            group_by_length=group_by_length,
            report_to="wandb" if use_wandb else None,
            run_name=wandb_run_name if use_wandb else None,
        ),
        data_collator=transformers.DataCollatorForSeq2Seq(
            tokenizer, pad_to_multiple_of=8, return_tensors="pt", padding=True
        ),
        # compute_metrics=compute_metrics
    )
    model.config.use_cache = False

```

### Expected behavior

Training as normal with seperate evaluation on each Dataset in the dict

[EDIT] the error occurs right after having validated every set. I can see that it starts training again.

Am I doing something wrong?
I really see anything wrong with the evaluation datasets that I'm using
They work when it's just one big evaluation Dataset object

If you need more info, please let me know :)
Not certain, but this may be related to #22885.<|||||>> Not certain, but this may be related to #22885.

Thanks for the reference, however the proposed workaround (`label_names=["labels"]`) did not work.

<|||||>Please post a reproducer we can execute.<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.