fix(ui): error when collapsing sidebar groups (#9393)

Fixes
https://discord.com/channels/967097582721572934/1308933812914229368/1308933812914229368

![CleanShot 2024-11-20 at 19 04
45@2x](https://github.com/user-attachments/assets/3c2c8054-9d09-4090-adf8-57aef8635baf)

packages/ui/src/providers/Preferences/index.tsx

@@ -99,7 +99,9 @@ export const PreferencesProvider: React.FC<{ children?: React.ReactNode }> = ({
         typeof newValue === 'object'
       ) {
         // merge the value with any existing preference for the key
-        newValue = deepMergeSimple(currentPreference, newValue)
+        if (currentPreference) {
+          newValue = deepMergeSimple(currentPreference, newValue)
+        }
 
         if (dequal(newValue, currentPreference)) {
           return