fix: skip PR creation if no prerelease changesets exist (#11729)

.github/workflows/prerelease.yml

@@ -73,10 +73,25 @@ jobs:
           git commit -m 'Enter prerelease mode'
           git push
 
+      - name: Get prerelease changesets
+        id: prerelease-changesets
+        uses: notiz-dev/github-action-json-property@release
+        with:
+          path: ".changeset/pre.json"
+          prop_path: "changesets"
+
+      - name: Get changesets array length
+        id: number-of-changesets
+        run: |
+          arrayLength=$(echo '${{steps.prerelease-changesets.outputs.prop}}' | jq '. | length')
+          echo "length=$arrayLength" >> "$GITHUB_OUTPUT"
+
       - name: Create prerelease PR
-        # If .changeset/pre.json exists and we are not currently cutting a
-        # release after merging a Version Packages PR
-        if: steps.check_files.outputs.files_exists == 'true' && !startsWith(github.event.head_commit.message, 'Version Packages')
+        # Only attempt to create a PR if:
+        # 1. .changeset/pre.json exists
+        # 2. we are not actively publishing after merging a Version Packages PR
+        # 3. AND we have prerelease changesets to publish (otherwise it errors)
+        if: steps.check_files.outputs.files_exists == 'true' && !startsWith(github.event.head_commit.message, 'Version Packages') && steps.number-of-changesets.outputs.length > 0
         uses: changesets/action@v1
         with:
           version: npm run changeset-version
@@ -85,8 +100,8 @@ jobs:
 
       - name: Publish to npm + GitHub
         id: changesets
-        # Only run publish if we're still in pre mode and the last commit was
-        # via an automatically created Version Packages PR
+        # Only publish if we're still in pre mode and the last commit was
+        # from an automatically created Version Packages PR
         if: steps.check_files.outputs.files_exists == 'true' && startsWith(github.event.head_commit.message, 'Version Packages')
         uses: changesets/action@v1
         with: