fix: Don't panic when receiving PDUs with illegal auth events

Apparently some servers do this??

src/service/rooms/event_handler/handle_outlier_pdu.rs

@@ -170,12 +170,13 @@ impl super::Service {
 				.expect("we just checked that we have all auth events")
 				.to_owned();
 
-			let key = auth_event.kind().with_state_key(
+			let Some(state_key) = auth_event.state_key() else {
-				auth_event
+				self.reject_and_persist(event_id, &incoming_pdu);
-					.state_key
+				return Err!(Request(Forbidden(debug_warn!(
-					.clone()
+					"Event references non-state event as an auth event: {id}",
-					.expect("all auth events must have state keys"),
+				))));
-			);
+			};
+			let key = auth_event.kind().with_state_key(state_key);
 			match auth_events_by_key.entry(key) {
 				| hash_map::Entry::Vacant(v) => {
 					v.insert(auth_event);

src/web/pages/account/register.rs

@@ -7,7 +7,7 @@ use axum::{
 	routing::{get, on},
 };
 use conduwuit_api::client_ip::ClientIp;
-use conduwuit_core::{config::TermsDocument, info, warn};
+use conduwuit_core::{config::TermsDocument, warn};
 use conduwuit_service::{
 	mailer::messages,
 	registration_tokens::ValidToken,