From 5a7bb1e8f104b66e65a16e447d930b478640383a Mon Sep 17 00:00:00 2001
From: Val Lorentz <progval+git@progval.net>
Date: Sat, 2 Dec 2023 17:51:19 +0100
Subject: [PATCH] Return error instead of panic when first event is not
 m.room.create

---
 src/service/rooms/timeline/mod.rs | 33 ++++++++++++++++++++-----------
 src/utils/error.rs                |  2 ++
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/src/service/rooms/timeline/mod.rs b/src/service/rooms/timeline/mod.rs
index a6e9f87a..06deb069 100644
--- a/src/service/rooms/timeline/mod.rs
+++ b/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(|| {
-            if event_type != TimelineEventType::RoomCreate {
-                panic!("non-create event for room of unknown version");
-            }
-            #[derive(Deserialize)]
-            struct RoomCreate {
-                room_version: RoomVersionId,
-            }
-            let content = serde_json::from_str::<RoomCreate>(content.get())
-                .expect("Invalid content in RoomCreate pdu.");
-            content.room_version
-        });
+        let room_version_id = self
+            .get_room_version(room_id)?
+            .or_else(|| {
+                if event_type == TimelineEventType::RoomCreate {
+                    #[derive(Deserialize)]
+                    struct RoomCreate {
+                        room_version: RoomVersionId,
+                    }
+                    let content = serde_json::from_str::<RoomCreate>(content.get())
+                        .expect("Invalid content in RoomCreate pdu.");
+                    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");
 
diff --git a/src/utils/error.rs b/src/utils/error.rs
index 83ef3095..568ad8a0 100644
--- a/src/utils/error.rs
+++ b/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 {