add warning for legacy config

scnewsbot/__main__.py

@@ -9,12 +9,21 @@ class InvalidTokenException(Exception):
     pass
 
 
+class InvalidConfigException(Exception):
+    pass
+
+
 def main() -> None:
     DISCORD_TOKEN = os.getenv("DISCORD_TOKEN")
     if not DISCORD_TOKEN:
         raise InvalidTokenException("A Discord token was not set.")
 
     with open("config.toml", "rb") as config_file:
+        if "[permissions]" in config_file.read():
+            raise InvalidConfigException(
+                "The format for permissions has changed; please check the new example config."
+            )
+
         config = Config(tomllib.load(config_file))
 
     bot = Bot(config)