Members is optional

src/types/events/passive_update.rs

@@ -9,7 +9,7 @@ use crate::types::{GuildMember, VoiceState};
 /// Seems to be passively set to update the client on guild details (though, why not just send the update events?)
 pub struct PassiveUpdateV1 {
     pub voice_states: Vec<VoiceState>,
-    pub members: Vec<GuildMember>,
+    pub members: Option<Vec<GuildMember>>,
     pub guild_id: String,
     pub channels: Vec<ChannelUnreadUpdateObject>,
 }