$ perl buggy_array.pl 2> out.txt

(it hangs here, press Ctrl-C to stop)

$ head -6 out.txt
Use of reference "ARRAY(0x1cfb148)" as array index at ary.pl line 21.
Use of uninitialized value in concatenation (.) or string at ary.pl line 21.
Use of reference "ARRAY(0x1d0fad8)" as array index at ary.pl line 21.
Use of uninitialized value in concatenation (.) or string at ary.pl line 21.
Use of reference "ARRAY(0x1d0fbf8)" as array index at ary.pl line 21.
Use of uninitialized value in concatenation (.) or string at ary.pl line 21.