message: Correctly handle the value is_null case in move_constants
diff: @@ -36,6 +36,9 @@ unique_ptr<Expression> MoveConstantsRule::Apply(LogicalOperator &op, vector<Expr
  if (!arithmetic->return_type.IsNumeric()) {
  return nullptr;
  }
  + if (inner_constant->value.is_null || outer_constant->value.is_null) {
  + return make_unique<BoundConstantExpression>(Value(comparison->return_type));
  + }
  int arithmetic_child_index = arithmetic->children[0].get() == inner_constant ? 1 : 0;
  auto &op_type = arithmetic->function.name;
  