fix(sdk): Deal with missing data in Sliding Sync's responses

fix(sdk): Deal with missing data in Sliding Sync's responses

crates/matrix-sdk/src/sliding_sync/room.rs

@@ -153,14 +153,33 @@ impl SlidingSyncRoom {
         } = room_data;
 
         self.inner.unread_notifications = unread_notifications;
-        self.inner.name = name;
-        self.inner.initial = initial;
-        self.inner.is_dm = is_dm;
-        self.inner.invite_state = invite_state;
-        self.inner.required_state = required_state;
 
-        if let Some(batch) = prev_batch {
-            Observable::set(&mut self.prev_batch.write().unwrap(), Some(batch));
+        // The server might not send some parts of the response, because they were sent
+        // before and the server wants to save bandwidth. So let's update the values
+        // only when they exist.
+
+        if name.is_some() {
+            self.inner.name = name;
+        }
+
+        if initial.is_some() {
+            self.inner.initial = initial;
+        }
+
+        if is_dm.is_some() {
+            self.inner.is_dm = is_dm;
+        }
+
+        if !invite_state.is_empty() {
+            self.inner.invite_state = invite_state;
+        }
+
+        if !required_state.is_empty() {
+            self.inner.required_state = required_state;
+        }
+
+        if prev_batch.is_some() {
+            Observable::set(&mut self.prev_batch.write().unwrap(), prev_batch);
         }
 
         // There is timeline updates.