Update app.py

app.py

@@ -114,6 +114,13 @@ def next_image(embs, ys, calibrate_prompts):
             # sample a .8 of rated embeddings for some stochasticity, or at least two embeddings.
             n_to_choose = max(int(len(embs)*.8), 2)
             indices = random.sample(range(len(embs)), n_to_choose)
+
+            # we may have just encountered a rare multi-threading diffusers issue (https://github.com/huggingface/diffusers/issues/5749);
+            # this ends up adding a rating but losing an embedding, it seems.
+            # let's take off a rating if so to continue without indexing errors.
+            if len(ys) > len(embs):
+                print('ys are longer than embs; popping latest rating')
+                ys.pop(-1)
             
             # also add the latest 0 and the latest 1
             has_0 = False