if sd_model is None, do not always try to load it

modules/sd_models.py

@@ -409,12 +409,16 @@ sd2_clip_weight = 'cond_stage_model.model.transformer.resblocks.0.attn.in_proj_w
 class SdModelData:
     def __init__(self):
         self.sd_model = None
+        self.was_loaded_at_least_once = False
         self.lock = threading.Lock()
 
     def get_sd_model(self):
+        if self.was_loaded_at_least_once:
+            return self.sd_model
+
         if self.sd_model is None:
             with self.lock:
-                if self.sd_model is not None:
+                if self.sd_model is not None or self.was_loaded_at_least_once:
                     return self.sd_model
 
                 try:
@@ -495,6 +499,7 @@ def load_model(checkpoint_info=None, already_loaded_state_dict=None):
 
     sd_model.eval()
     model_data.sd_model = sd_model
+    model_data.was_loaded_at_least_once = True
 
     sd_hijack.model_hijack.embedding_db.load_textual_inversion_embeddings(force_reload=True)  # Reload embeddings after model load as they may or may not fit the model