handle case when controlnet is list or tuple (huggingface#5179)

* handle case when controlnet is list

* Update src/diffusers/loaders.py

* Apply suggestions from code review

* Update src/diffusers/loaders.py

* typecheck comment

---------

Co-authored-by: Patrick von Platen <[email protected]>

Author: noskill

src/diffusers/loaders.py

@@ -2433,8 +2433,8 @@ def from_single_file(cls, pretrained_model_link_or_path, **kwargs):
             from .models.controlnet import ControlNetModel
             from .pipelines.controlnet.multicontrolnet import MultiControlNetModel
 
-            # Model type will be inferred from the checkpoint.
-            if not isinstance(controlnet, (ControlNetModel, MultiControlNetModel)):
+            #  list/tuple or a single instance of ControlNetModel or MultiControlNetModel
+            if not (isinstance(controlnet, (ControlNetModel, MultiControlNetModel)) or isinstance(controlnet, (list, tuple)) and isinstance(controlnet[0], ControlNetModel)):
                 raise ValueError("ControlNet needs to be passed if loading from ControlNet pipeline.")
         elif "StableDiffusion" in pipeline_name:
             # Model type will be inferred from the checkpoint.