Handle null child query

Description

Fixes null reference errors when collecting styles if ChildQuery has a null node.

[ ] ✨ New feature: Adds new functionality without breaking existing features.
[x] 🛠️ Bug fix: Resolves an issue without altering current behavior.
[ ] 🧹 Code refactor: Code restructuring that does not affect behavior.
[ ] ❌ Breaking change: Alters existing functionality and requires updates.
[ ] 🧪 Tests: Adds new tests or modifies existing tests.
[ ] 📝 Documentation: Updates or additions to documentation.
[ ] 🗑️ Chore: Routine tasks, or maintenance.
[ ] ✅ Build configuration change: Changes to build or deploy processes.