Update app.py

app.py

@@ -48,10 +48,12 @@ def getChooseRole(msg):
 
 def getChooseClass(msg):
     full = getChooseRole(msg)
-    if 
-    start_index = full.index(" ") + len(" ")
-    end_index = msg.index(",")
-    return trim(full[start_index:] + full[:end_index])
+    if full != "":
+        start_index = full.index(" ") + len(" ")
+        end_index = msg.index(",")
+        return trim(full[start_index:] + full[:end_index])
+    else:
+        return ""
 
 def chatbot(input, messages):
     messages = messages or [{"role": "system", "content": initMsg}]