Make "Update release branch" workflow fail if npm version fails

.github/update-release-branch.py

@@ -88,6 +88,7 @@ def open_pr(
   body.append('')
   body.append('Please review the following:')
   if len(conflicted_files) > 0:
+    body.append('- The package.json file contains the correct version.')
     body.append(' - [ ] You have added commits to this branch that resolve the merge conflicts ' +
       'in the following files:')
     body.extend([f'    - [ ] `{file}`' for file in conflicted_files])
@@ -296,15 +297,15 @@ def main():
 
     # Migrate the package version number from a v2 version number to a v1 version number
     print(f'Setting version number to {version}')
-    subprocess.run(['npm', 'version', version, '--no-git-tag-version'])
+    subprocess.check_output(['npm', 'version', version, '--no-git-tag-version'])
     run_git('add', 'package.json', 'package-lock.json')
 
     # Migrate the changelog notes from v2 version numbers to v1 version numbers
     print('Migrating changelog notes from v2 to v1')
-    subprocess.run(['sed', '-i', 's/^## 2\./## 1./g', 'CHANGELOG.md'])
+    subprocess.check_output(['sed', '-i', 's/^## 2\./## 1./g', 'CHANGELOG.md'])
 
     # Remove changelog notes from v2 that don't apply to v1
-    subprocess.run(['sed', '-i', '/^- \[v2+ only\]/d', 'CHANGELOG.md'])
+    subprocess.check_output(['sed', '-i', '/^- \[v2+ only\]/d', 'CHANGELOG.md'])
 
     # Amend the commit generated by `npm version` to update the CHANGELOG
     run_git('add', 'CHANGELOG.md')