fix(room_member): Strip join_authorized_via_users_server (#1542)

Some clients were sending join_authorized_via_users_server when they
were already in the room, to change nicknames. This caused an undesirable
error, so a check for if they were already in the room was moved and
changed to strip from metadata before attempting to process metadata.

Signed-off-by: Jonathan Sutton <jonathansutton91@proton.me>

src/api/client/state.rs

@@ -366,30 +366,28 @@ async fn allowed_to_send_state_event(
 			}
 		},
 		| StateEventType::RoomMember => match json.deserialize_as::<RoomMemberEventContent>() {
-			| Ok(membership_content) => {
+			| Ok(mut membership_content) => {
 				let Ok(state_key) = UserId::parse(state_key) else {
 					return Err!(Request(BadJson(
 						"Membership event has invalid or non-existent state key"
 					)));
 				};
 
-				if let Some(authorising_user) =
+				// Moved the check for if user is already joined and then stripped the Option
-					membership_content.join_authorized_via_users_server
+				// Unsure if this actually fixes it
-				{
-					if membership_content.membership != MembershipState::Join {
-						return Err!(Request(BadJson(
-							"join_authorised_via_users_server is only for member joins"
-						)));
-					}
-
 				if services
 					.rooms
 					.state_cache
 					.is_joined(state_key, room_id)
 					.await
 				{
-						return Err!(Request(InvalidParam(
+					membership_content.join_authorized_via_users_server.take();
-							"{state_key} is already joined, an authorising user is not required."
+				} else if let Some(authorising_user) =
+					membership_content.join_authorized_via_users_server
+				{
+					if membership_content.membership != MembershipState::Join {
+						return Err!(Request(BadJson(
+							"join_authorised_via_users_server is only for member joins"
 						)));
 					}