Resolve AttributeError in issue_filer.py

Safeguard the process of issue filing by ensuring presence
of attributes within Issue variants before accessing them.

Author: AashutoshMurthy

src/clusterfuzz/_internal/issue_management/issue_filer.py

@@ -493,9 +493,9 @@ def file_issue(testcase,
     if issue_tracker.project == 'google-buganizer':
       logs.info('The values of Component IDs:')
       logs.info(f'1. Backing: {list(issue.components)}')
-      removed = list(getattr(issue.components, 'removed', None))
+      removed = list(getattr(issue.components, 'removed', []))
       logs.info(f'2. Removed: {removed}')
-      added = list(getattr(issue.components, 'added', None))
+      added = list(getattr(issue.components, 'added', []))
       logs.info(f'3. Added: {added}')
     logs.info('Primary attempt to the save the issue.')
     issue.save()