Show which element(s) are involved at each error point:
- When an element is missing the "key" attribute, show the element
- When an element is not an attribute set, show the element
- When comparing keys fails, show both elements being compared
- When calling operator fails, show which element was being processed
This provides concrete context using ValuePrinter with errorPrintOptions.
Note: errorPrintOptions uses maxDepth=10 by default, which may print
quite deeply nested structures in error messages. This could potentially
be overwhelming, but follows the existing default for error contexts.
