check if file is even added

.github/workflows/flake-update.yml

@@ -36,10 +36,11 @@ jobs:
               run: |
                 wget --content-disposition -nv "$DETERMINATE_URL"
 
-                git diff --quiet
+                git diff --quiet && git ls-files --error-unmatch "$DETERMINATE_BINARY"
                 echo "DETERMINATE_BINARY_DIFF=$?" | tee -a "$GITHUB_OUTPUT"
               env:
                 DETERMINATE_URL: ${{ env.DETERMINATE_URL }}
+                DERMINATE_BINARY: ${{ env.DETERMINATE_BINARY }}
     commit-data:
         runs-on: ubuntu-latest
         needs: download-binary