ABAP Short Dump on append of a sorted table ITAB_ILLEGAL_SORT_ORDER

The program short dumps when appending a sorted table in the wrong sort order

data: sorted_tab type sorted table of ty_tab with non-unique key key,
      line       type ty_tab.

line-key = 1.
append line to sorted_tab.  "works fine"

line-key = 2.
append line to sorted_tab.  "works fine"

line-key = 1.
append line to sorted_tab.  "<==== Short dump here"
           

Use INSERT in stead:

data: sorted_tab type sorted table of ty_tab with non-unique key key,
      line       type ty_tab.

line-key = 1.
insert line into table sorted_tab.  "works fine"

line-key = 2.
insert line into table sorted_tab.  "works fine"    

line-key = 1.
insert line into table sorted_tab.  "works fine"