Return error instead of panic when first event is not m.room.create

src/service/rooms/timeline/mod.rs

@@ -696,18 +696,27 @@ impl Service {
             .collect();
 
         // If there was no create event yet, assume we are creating a room
-        let room_version_id = self.get_room_version(room_id)?.unwrap_or_else(|| {
+        let room_version_id = self
-            if event_type != TimelineEventType::RoomCreate {
+            .get_room_version(room_id)?
-                panic!("non-create event for room of unknown version");
+            .or_else(|| {
-            }
+                if event_type == TimelineEventType::RoomCreate {
-            #[derive(Deserialize)]
+                    #[derive(Deserialize)]
-            struct RoomCreate {
+                    struct RoomCreate {
-                room_version: RoomVersionId,
+                        room_version: RoomVersionId,
-            }
+                    }
-            let content = serde_json::from_str::<RoomCreate>(content.get())
+                    let content = serde_json::from_str::<RoomCreate>(content.get())
-                .expect("Invalid content in RoomCreate pdu.");
+                        .expect("Invalid content in RoomCreate pdu.");
-            content.room_version
+                    Some(content.room_version)
-        });
+                } else {
+                    None
+                }
+            })
+            .ok_or_else(|| {
+                Error::InconsistentRoomState(
+                    "non-create event for room of unknown version",
+                    room_id.to_owned(),
+                )
+            })?;
 
         let room_version = RoomVersion::new(&room_version_id).expect("room version is supported");
 

src/utils/error.rs

@@ -82,6 +82,8 @@ pub enum Error {
     PathError(#[from] axum::extract::rejection::PathRejection),
     #[error("from {0}: {1}")]
     RedactionError(OwnedServerName, ruma::canonical_json::RedactionError),
+    #[error("{0} in {1}")]
+    InconsistentRoomState(&'static str, ruma::OwnedRoomId),
 }
 
 impl Error {