[data_loader] expand the error message (#2221)

* Update data_loader.py

* style

src/accelerate/data_loader.py

@@ -152,7 +152,10 @@ def __init__(
         self.batch_size = getattr(batch_sampler, "batch_size", None)
         self.drop_last = getattr(batch_sampler, "drop_last", False)
         if self.batch_size is None and self.even_batches:
-            raise ValueError("You need to use `even_batches=False` when the batch sampler has no batch size.")
+            raise ValueError(
+                "You need to use `even_batches=False` when the batch sampler has no batch size. If you "
+                "are not calling this method directly, set `accelerator.even_batches=False` instead."
+            )
 
     @property
     def total_length(self):