Account for no changes in previous step for scheduled_update.yaml

.github/workflows/scheduled_update.yaml

@@ -60,15 +60,17 @@ jobs:
       - run: |
           gh repo sync
           tag=$(git describe --tags --abbrev=0) || release_needed="true"
-          for file in $(git diff ${tag}..${{ needs.update.outputs.sha }} --name-only); do
+          sha=${{ needs.update.outputs.sha }}
+          if [ -z "${sha}" ]; then sha="HEAD"; fi
+          for file in $(git diff ${tag}..${sha} --name-only); do
             if [ $file == "taginfo.json" ] || [ $file == "index.json" ] || [ $file == "package.json"] ; then
               release_needed="true"
               break
             fi
           done
           if [ $release_needed == "true" ]; then
             tag=$(jq -r '.version' package.json)
-            object=$(git rev-parse --verify ${{ needs.update.outputs.sha }})
+            object=$(git rev-parse --verify ${sha})
             gh api --method POST -H "Accept: application/vnd.github+json" -H "X-GitHub-Api-Version: 2022-11-28" \
               /repos/${{ github.repository }}/git/tags \
               --field "tag=${tag}" \