fix conversion of checkpoints into incompatible diffusers models

- The checkpoint conversion script was generating diffusers models
  with the safety checker set to null. This resulted in models
  that could not be merged with ones that have the safety checker
  activated.

- This PR fixes the issue by incorporating the safety checker into
  all 1.x-derived checkpoints, regardless of user's nsfw_checker setting.

ldm/invoke/CLI.py

@@ -786,6 +786,7 @@ def optimize_model(model_name_or_path: Union[Path,str], gen, opt, completer):
     model_name_or_path = model_name_or_path.replace('\\','/') # windows
     manager = gen.model_manager
     ckpt_path = None
+    original_config_file=None
 
     if model_name_or_path == gen.model_name:
         print("** Can't convert the active model. !switch to another model first. **")

ldm/invoke/ckpt_to_diffuser.py

@@ -53,6 +53,7 @@ from diffusers import (
 )
 from diffusers.pipelines.latent_diffusion.pipeline_latent_diffusion import LDMBertConfig, LDMBertModel
 from diffusers.pipelines.paint_by_example import PaintByExampleImageEncoder, PaintByExamplePipeline
+from diffusers.pipelines.stable_diffusion.safety_checker import StableDiffusionSafetyChecker
 from diffusers.utils import is_safetensors_available
 from transformers import AutoFeatureExtractor, BertTokenizerFast, CLIPTextModel, CLIPTokenizer, CLIPVisionConfig
 
@@ -984,6 +985,7 @@ def load_pipeline_from_original_stable_diffusion_ckpt(
         elif model_type in ['FrozenCLIPEmbedder','WeightedFrozenCLIPEmbedder']:
             text_model = convert_ldm_clip_checkpoint(checkpoint)
             tokenizer = CLIPTokenizer.from_pretrained("openai/clip-vit-large-patch14",cache_dir=cache_dir)
+            safety_checker = StableDiffusionSafetyChecker.from_pretrained('CompVis/stable-diffusion-safety-checker',cache_dir=global_cache_dir("hub"))
             feature_extractor = AutoFeatureExtractor.from_pretrained("CompVis/stable-diffusion-safety-checker",cache_dir=cache_dir)
             pipe = pipeline_class(
                 vae=vae,
@@ -991,7 +993,7 @@ def load_pipeline_from_original_stable_diffusion_ckpt(
                 tokenizer=tokenizer,
                 unet=unet,
                 scheduler=scheduler,
-                safety_checker=None,
+                safety_checker=safety_checker,
                 feature_extractor=feature_extractor,
             )
         else: