~~~
:err:set-handler (nn-)
  #1234 io:scan-for
    dup n:negative? [ drop 'Error:_device_(1234)_not_found s:put nl ] if;
    #0 swap io:invoke ;

:err:dsu (-)
  reset nl 'ERROR:_DSU:_DATA_STACK_UNDERFLOW s:put nl bye ;

:err:dso (-)
  reset nl 'ERROR:_DSO:_DATA_STACK_OVERFLOW s:put nl bye ;

:err:set-defaults
  &err:dsu #1 err:set-handler
  &err:dso #2 err:set-handler ;

'interface/error.retro s:keep
dup 'err:set-handler  d:lookup d:source store
dup 'err:set-defaults d:lookup d:source store
dup 'err:dso          d:lookup d:source store
dup 'err:dsu          d:lookup d:source store
drop
~~~