fix(properties-panel): enhance element detection and error handling for nested structures

readme.plan.md

@@ -61,4 +61,28 @@ The properties panel has timing issues detecting rendered elements because:
 - Access children via wrapper.children property
 - Updated documentation with correct import path (lowercase 'demotools')
 - Examples show how to use querySelector for powerful element selection
-- Added clarifying comment about querySelector working on slotted content
+- Added clarifying comment about querySelector working on slotted content
+
+## Fixed Properties Panel Compatibility:
+- Made element search generic - works with any container elements
+- Searches both light DOM and shadow DOM recursively
+- Improved error handling to prevent breaking the update cycle
+- Errors in one property don't prevent others from rendering
+- Detection continues working even after errors occur
+- Maintains compatibility with all element structures
+
+# Test Elements Created (COMPLETED)
+
+## Created comprehensive test elements:
+1. **test-noprops** - Element with no @property decorators
+2. **test-complextypes** - Element with arrays, objects, dates, and complex nested data
+3. **test-withwrapper** - Element that uses dees-demowrapper in its demo
+4. **test-edgecases** - Element with edge cases (null, undefined, NaN, Infinity, circular refs)
+5. **test-nested** - Element with deeply nested structure to test recursive search
+
+These test various scenarios:
+- Properties panel handling of elements without properties
+- Complex data type display and editing
+- Element detection inside dees-demowrapper
+- Error handling for problematic values
+- Deep nesting and shadow DOM traversal