Update tangger/Qwen-7B-Chat since Qwen/Qwen-7B-Chat is gone

.gitignore

@@ -1 +1,2 @@
 .ruff_cache
+__pycache__

app.py

@@ -60,7 +60,8 @@ except Exception:
     # Windows
     logger.warning("Windows, cant run time.tzset()")
 
-model_name = "Qwen/Qwen-7B-Chat"
+model_name = "Qwen/Qwen-7B-Chat"  # gone!
+model_name = "tangger/Qwen-7B-Chat"  # try
 tokenizer = AutoTokenizer.from_pretrained(model_name, trust_remote_code=True)
 
 n_gpus = torch.cuda.device_count()
@@ -168,9 +169,13 @@ def bot(chat_history, **kwargs):
 
 
 def bot_stream(chat_history, **kwargs):
-    logger.trace(f"{chat_history=}")
     logger.trace(f"{kwargs=}")
 
+    # somehow, empty chat_history
+    if chat_history is None or not chat_history:
+        logger.trace(f" *** {chat_history=}")
+        chat_history.append(["", ""])
+
     try:
         message = chat_history[-1][0]
     except Exception as exc: