Optimizer trace for DELETE query shows table:null

create table ten(a int);

insert into ten values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

create table t10 (a int, b int);

insert into t10 select a,a from ten;

alter table t10 add key(a);

set optimizer_trace=1;

explain delete from t10 where t10.a<3;

select * from information_schema.optimizer_trace\G 

*************************** 1. row ***************************

                            QUERY: explain delete from t10 where t10.a<3

                            TRACE: {

  "steps": [

    {

      "table": null,

      "range_analysis": {

        "table_scan": {

          "rows": 10,

          "cost": 5.1

        },

        "potential_range_indexes": [