.append does stuff in place

rplugin/python3/handlers/chat_handler.py

@@ -224,10 +224,10 @@ def _add_chat_messages(
             if last_newline == -1:
                 continue
             # If there is a newline, take everything in front of it and set that as the token
-            token = buffer[: last_newline]
+            token = buffer[: last_newline + 1]
 
             # Remove the token and newline from the buffer
-            buffer = buffer.replace(token + "\n", "")
+            buffer = buffer.replace(token, "")
             self.nvim.exec_lua(
                 'require("CopilotChat.utils").log_info(...)', f"Token: {token}"
             )
@@ -241,7 +241,7 @@ def _add_chat_messages(
                 last_line_col,
                 last_line_row,
                 last_line_col,
-                [tok.encode('utf-8') for tok in token.split("\n").append("")],
+                [tok.encode('utf-8') for tok in token.split("\n")],
             )
 
         buffer_lines = cast(list[str], self.buffer.lines())