fix: files_metadata (#2645)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

backend/modules/sync/entity/sync.py

@@ -20,7 +20,7 @@ class SyncsActive(BaseModel):
     last_synced: datetime
     sync_interval_minutes: int
     brain_id: str
-    syncs_user: Optional[SyncsUser]
+    syncs_user: Optional[SyncsUser] = None
 
 
 class SyncsFiles(BaseModel):

backend/modules/sync/utils/googleutils.py

@@ -266,6 +266,7 @@ class GoogleSyncUtils(BaseModel):
         folders = settings.get("folders", [])
         files_to_download = settings.get("files", [])
         files = []
+        files_metadata = []
         if len(folders) > 0:
             files = []
             for folder in folders:

backend/modules/sync/utils/sharepointutils.py

@@ -260,6 +260,7 @@ class AzureSyncUtils(BaseModel):
         folders = settings.get("folders", [])
         files_to_download = settings.get("files", [])
         files = []
+        files_metadata = []
         if len(folders) > 0:
             files = []
             for folder in folders: