revert the erroneous change for model setting added in df02498d

modules/processing.py

@@ -595,8 +595,7 @@ def process_images(p: StableDiffusionProcessing) -> Processed:
 
     try:
         # if no checkpoint override or the override checkpoint can't be found, remove override entry and load opts checkpoint
-        override_checkpoint = p.override_settings.get('sd_model_checkpoint')
-        if override_checkpoint is not None and sd_models.checkpoint_alisases.get(override_checkpoint) is None:
+        if sd_models.checkpoint_alisases.get(p.override_settings.get('sd_model_checkpoint')) is None:
             p.override_settings.pop('sd_model_checkpoint', None)
             sd_models.reload_model_weights()