I get the same error when click on some "talk to" button on demo:
E 0:00:41.560 get_node: Node not found: MSG_pos.
<C++ Error> Condition "!node" is true. Returned: __null
<C++ Source> scene/main/node.cpp:1381 @ get_node()
<Stack Trace> MSG_Parser.gd:266 @ update_text()
MSG_Parser.gd:164 @ next()
MSG_Parser.gd:253 @ _auto_next()
MSG_Parser.gd:198 @ next()
MSG_Parser.gd:253 @ _auto_next()
MSG_Parser.gd:103 @ start_dialogue()
Character.gd:13 @ talk()
talk_button.gd:9 @ on_pressed()
at 206 line of MSG_Parser.gd:
if current_speaker.get_node("MSG_pos"):