set labels and fix datasets block

src/axolotl/prompt_strategies/pretrain.py

@@ -41,6 +41,7 @@ class PretrainTokenizationStrategy(PromptTokenizingStrategy):
             seq + [self.tokenizer.eos_token_id] for seq in res["input_ids"]
         ]
         res["attention_mask"] = [seq + [1] for seq in res["attention_mask"]]
+        res["labels"] = res["input_ids"].copy()
 
         return res
 
@@ -52,7 +53,7 @@ def load(tokenizer, cfg):
     if cfg.pretraining_dataset:
         cfg_ds = cfg.pretraining_dataset
     else:
-        cfg_ds = cfg.dataset
+        cfg_ds = cfg.datasets
     strat = PretrainTokenizationStrategy(
         PretrainTokenizer(),
         tokenizer,