Added name symbol validation.

webui.py

@@ -1,6 +1,6 @@
 from nicegui import ui
-from pandas.core.internals.blocks import external_values
 from bot_instance import bot
+import re
 from dom5game import Dom5game
 import servermanager
 import os
@@ -44,7 +44,10 @@ def creator_page():
         validation={
             "Game with that name already exists": lambda value: not (
                 os.path.isdir("games/" + value)
-            )
+            ),
+            "Name contains an invalid symbol": lambda value: bool(
+                re.match("^[A-Za-z0-9_-]*$", value)
+            ),
         },
     )
     # Port