Fix `Guild` deser without `system_channel_id`

Fix the deserialization of `model::guild::Guild` when
`Guild::system_channel_id` is not present.

Additionally, add a test case for this.

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/test_deser.rs b/tests/test_deser.rs
index b17fe3c..ae9536b 100644
--- a/tests/test_deser.rs
+++ b/tests/test_deser.rs
@@ -178,3 +178,10 @@ fn message_type_7() {
 fn guild_features_deser() {
     p!(GuildCreateEvent, "guild_create_features");
 }
+
+// Ensure that `Guild`s still deserialize despite the `system_channel_id` key
+// missing.
+#[test]
+fn guild_system_channel_id_missing() {
+    p!(Guild, "guild_system_channel_id_missing");
+}