ORA-00604: Error occurred at recursive SQL level … Check subsequent errors.

truncate table plan_table;
alter table plan_table modify object_name varchar2(1);

explain plan for select dummy from dual;
-- ORA-00604: error occurred at recursive SQL level 1
-- ORA-12899: value too large for column "RENE"."PLAN_TABLE"."OBJECT_NAME" (actual: 4, maximum: 1)

alter table plan_table modify object_name varchar2(128);
explain plan for select dummy from dual;