fix: handle successful run without an open issue

.github/workflows/schedule.sgid-index-validation.yml

@@ -79,7 +79,7 @@ jobs:
               state: 'open',
               labels: 'sgid index validation'
             });
-            const issueNumber = issues[0].number;
+            const issueNumber = issues[0]?.number;
             console.log('issueNumber: ' + issueNumber);
 
             return issueNumber;
@@ -88,13 +88,15 @@ jobs:
 
       - name: Find Comment
         uses: peter-evans/find-comment@v3
+        if: steps.create-issue.outputs.number || steps.find-issue.outputs.result
         id: find-comment
         with:
           issue-number: ${{ steps.create-issue.outputs.number || steps.find-issue.outputs.result }}
           comment-author: github-actions[bot]
           body-includes: Validation Output
 
       - name: ✍️ Updating issue comment
+        if: steps.create-issue.outputs.number || steps.find-issue.outputs.result
         uses: peter-evans/create-or-update-comment@v4
         with:
           issue-number: ${{ steps.create-issue.outputs.number || steps.find-issue.outputs.result }}