Summary

• Changes incorrect access:signals-all to be the correct access:siem
• Adds a boom transformer to push back better error messages to the client in some cases

Checklist

Use strikethroughs to remove checklist items you don't feel are applicable to this PR.

- [ ] This was checked for cross-browser compatibility, including a check against IE11

- [ ] Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support

- [ ] Documentation was added for features that require explanation or tutorials

• Unit or functional tests were updated or added to match the most common scenarios

- [ ] This was checked for keyboard-only and screenreader accessibility

For maintainers

- [ ] This was checked for breaking API changes and was labeled appropriately

• This includes a feature addition or change that requires a release note and was labeled appropriately