validate inputs comprehensively

Ensure thorough input validation and comprehensive edge case handling in database operations. This includes checking parameter validity, handling null inputs, testing boundary conditions, and covering all comparison operators or function variants.

Key practices:

• Validate input parameters before processing (check for null pointers, out-of-bounds indices, type mismatches)
• Verify logical preconditions (e.g., check if bound column reference matches expected indexed column before modifying)
• Add comprehensive test coverage for edge cases, error conditions, and all supported operations
• Handle missing or incomplete cases (e.g., add missing comparison operators like IS [NOT] DISTINCT)

Example from column binding validation:

case ExpressionClass::BOUND_COLUMN_REF: {
    auto &bound_column_ref_expr = expr->Cast<BoundColumnRefExpression>();
    // Validate that the bound column actually matches the indexed column
    if (bound_column_ref_expr.binding.column_index == indexed_columns[0]) {
        for (idx_t i = 0; i < input_column_ids.size(); ++i) {
            if (input_column_ids[i] == indexed_columns[0]) {
                bound_column_ref_expr.binding.column_index = i;
                return;
            }
        }
    }
}

This approach prevents logic errors, improves reliability, and ensures database operations handle all valid inputs and edge cases correctly.