Fix legacy StableDiffusionPipeline init crash (#6969)

[srlynch1]

Eval r2 fix for huggingface#6969: scalar guard in register_modules, TypeError in _fetch_class_library_tuple, 4 fast tests green.

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Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Scalar skips config key
  • Changed the scalar branch in register_modules to register (None, None) in config like the None path, so config keys stay aligned with the init signature and .components no longer raises ValueError.

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Preview (496169cb19)

diff --git a/src/diffusers/pipelines/pipeline_utils.py b/src/diffusers/pipelines/pipeline_utils.py
--- a/src/diffusers/pipelines/pipeline_utils.py
+++ b/src/diffusers/pipelines/pipeline_utils.py
@@ -215,7 +215,7 @@
             elif isinstance(module, (bool, int, float, str)):
                 # Scalar values (e.g. bool mis-passed as image_encoder from legacy super().__init__) are not
                 # model components — skip library tuple registration. See https://github.com/huggingface/diffusers/issues/6969
-                register_dict = {}
+                register_dict = {name: (None, None)}
             else:
                 library, class_name = _fetch_class_library_tuple(module)
                 register_dict = {name: (library, class_name)}

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[cursor]

Scalar skips config key

Medium Severity

When register_modules receives a scalar component (e.g. a bool mis-bound to image_encoder), it sets an empty register_dict and skips register_to_config, unlike None which records (None, None). The attribute is still set, but the config omits that module name. components builds keys from config and then requires they match the init signature, so legacy-init pipelines can raise ValueError after init succeeds.

 

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