Fix OpenAI API with new param (show_after), closes #6747 (#6749)

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Co-authored-by: oobabooga <[email protected]>

Author: kelvie

modules/chat.py

@@ -412,7 +412,7 @@ def generate_chat_reply(text, state, regenerate=False, _continue=False, loading_
             yield history
             return
 
-    show_after = html.escape(state["show_after"]) if state["show_after"] else None
+    show_after = html.escape(state.get("show_after")) if state.get("show_after") else None
     for history in chatbot_wrapper(text, state, regenerate=regenerate, _continue=_continue, loading_message=loading_message, for_ui=for_ui):
         if show_after:
             after = history["visible"][-1][1].partition(show_after)[2] or "*Is thinking...*"