Fixed a bug for encoder.

app.py

@@ -86,7 +86,7 @@ def evaluate_stream(msg, history, temperature, top_p):
 
     # TODO: Avoid the tokens are too long.
     CUTOFF = 160 
-    while tokenizer.encode(context) > CUTOFF:
+    while len(tokenizer.encode(context)) > CUTOFF:
         # save 15 token size for the answer
         context = context[15:]