Cleanup step shows 'Bad credentials' error when prepare phase fails

[gireesh-fractal]

Description

When the prepare phase of the action fails (e.g., due to track_progress being used with an unsupported event type), the post-run cleanup step still attempts to delete the installation token, resulting in a confusing "Bad credentials" error in the logs.

Steps to Reproduce

1. Configure workflow with track_progress: true
2. Trigger via workflow_dispatch (unsupported event for track_progress)
3. Observe prepare phase fails with:

   ##[error]Prepare step failed with error: track_progress is only supported for events: pull_request, issues, issue_comment, pull_request_review_comment, pull_request_review. Current event: workflow_dispatch
   

4. Cleanup step then runs and shows:

   curl -L \
     -X DELETE \
     -H "Accept: application/vnd.github+json" \
     -H "Authorization: Bearer " \
     ...
   {
     "message": "Bad credentials",
     "documentation_url": "https://docs.github.com/rest",
     "status": "401"
   }
   

Note the empty token value after "Authorization: Bearer ".

Expected Behavior

The cleanup step should check if a token was successfully acquired before attempting to delete it:

if [ -n "$TOKEN" ]; then
  curl -L -X DELETE ...
fi

Actual Behavior

Cleanup runs unconditionally, resulting in a 401 error that can confuse users debugging workflow failures.

Impact

• Cosmetic/low severity - doesn't affect functionality
• Makes logs harder to interpret when debugging failures
• Users may think there's a credentials/permissions issue when the real error is elsewhere

Environment

• Action version: v1
• Event: workflow_dispatch
• Runner: ubuntu-latest