fix model loading twice in some situations

modules/sd_hijack.py

@@ -216,6 +216,9 @@ class StableDiffusionModelHijack:
         self.comments = []
 
     def get_prompt_lengths(self, text):
+        if self.clip is None:
+            return "-", "-"
+
         _, token_count = self.clip.process_texts([text])
 
         return token_count, self.clip.get_target_prompt_token_count(token_count)