Treat an absent East Asian name order answer as unset

Pretix omits unticked boolean answers from a position's answer list
entirely, rather than sending them with a false value. generate_nickname
subscripted "east_asian_name_order" directly, so any order whose holder
left that checkbox unticked raised KeyError.

The exception escaped to the 500 handler, so /join returned the error
page instead of redirecting into the Discord OAuth2 flow. This affected
every attendee who supplied a name and did not tick the box.

Read the answer with .get() so an absent value falls through to the
default name ordering, which is the intended behaviour when East Asian
name order has not been requested.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: devjack

src/precord/values.py

@@ -54,7 +54,7 @@ def generate_nickname(answers: dict[str, Any]) -> str | None:
     """Generate the nickname to use on the server based on answers in the order."""
     if "primary_name" not in answers:
         return None
-    if answers["east_asian_name_order"] == "True":
+    if answers.get("east_asian_name_order") == "True":
         return f"{answers.get('additional_names', '')} {answers['primary_name']}"
     return f"{answers['primary_name']} {answers.get('additional_names', '')}"