Don't use load_state_dict if torch is not installed.

src/diffusers/modeling_flax_utils.py

@@ -28,7 +28,6 @@ from huggingface_hub.utils import EntryNotFoundError, RepositoryNotFoundError, R
 from requests import HTTPError
 
 from .modeling_flax_pytorch_utils import convert_pytorch_state_dict_to_flax
-from .modeling_utils import load_state_dict
 from .utils import (
     CONFIG_NAME,
     DIFFUSERS_CACHE,
@@ -37,6 +36,7 @@ from .utils import (
     WEIGHTS_NAME,
     logging,
 )
+from . import is_torch_available
 
 
 logger = logging.get_logger(__name__)
@@ -391,6 +391,14 @@ class FlaxModelMixin:
                 )
 
         if from_pt:
+            if is_torch_available():
+                from .modeling_utils import load_state_dict
+            else:
+                raise EnvironmentError(
+                    f"Can't load the model in PyTorch format because PyTorch is not installed. "
+                    f"Please, install PyTorch or use native Flax weights."
+                )
+
             # Step 1: Get the pytorch file
             pytorch_model_file = load_state_dict(model_file)