diff --git a/src/matrix/room/timeline/FragmentIdComparer.js b/src/matrix/room/timeline/FragmentIdComparer.js
index c26aa043..d88b257b 100644
--- a/src/matrix/room/timeline/FragmentIdComparer.js
+++ b/src/matrix/room/timeline/FragmentIdComparer.js
@@ -134,6 +134,13 @@ export default class FragmentIdComparer {
 
     rebuild(fragments) {
         const islands = createIslands(fragments);
+        const fragmentJson = JSON.stringify(islands.map(i => {
+            return Array.from(i._idToSortIndex.entries())
+                .map(([id, idx]) => {return {id, idx};})
+                .sort((a, b) => a.idx - b.idx);
+        }));
+        const firstFragment = this._fragmentsById.values().next().value;
+        console.log("rebuilt fragment index", firstFragment && firstFragment.roomId, fragmentJson);
         this._idToIsland = new Map();
         for(let island of islands) {
             for(let id of island.fragmentIds) {
diff --git a/src/matrix/room/timeline/Timeline.js b/src/matrix/room/timeline/Timeline.js
index 99828479..353b8634 100644
--- a/src/matrix/room/timeline/Timeline.js
+++ b/src/matrix/room/timeline/Timeline.js
@@ -33,7 +33,13 @@ export default class Timeline {
 
     /** @package */
     appendLiveEntries(newEntries) {
-        this._remoteEntries.setManySorted(newEntries);
+        try {
+            this._remoteEntries.setManySorted(newEntries);
+        } catch (err) {
+            console.error("error while appending live entries in roomId", this._roomId);
+            console.error(err.stack);
+            throw err;
+        }
     }
 
     /** @public */