Replace `.unwrap()` calls and sentinel values with safe null handling patterns to prevent runtime panics and improve code robustness. **Key Issues:** 1. **Unsafe unwrapping**: Using `.unwrap()` on operations that could fail, especially downcasts and IPC operations 2. **Sentinel values**: Using invalid constants like `Invalid` or `None = -1` instead of proper Option types 3. **Missing graceful degradation**: Not handling None cases appropriately **Safe Patterns:** - Use `if let Some(value) = optional_value` instead of `.unwrap()` - Use `.expect("meaningful message")` when unwrapping is truly safe - Replace sentinel values with `Option` types - Use `?` operator for early returns with Options - Return `Option` instead of default values when absence is meaningful **Example:** ```rust // ❌ Unsafe - could panic let video_elem = self.downcast::().unwrap(); video_elem.resize(width, height); // ✅ Safe pattern if let Some(video_elem) = self.downcast::() { video_elem.resize(width, height); } // ❌ Sentinel value antipattern pub enum LargestContentfulPaintType { None = -1, // ... } // ✅ Proper Option usage pub fn get_lcp_candidate() -> Option { // ... } ``` This prevents runtime crashes and makes null states explicit in the type system, improving both safety and code clarity.