First, let me apologize for not seeing the filter buttons at the top of the page.  I now see the response.  I suspected that modifying the basic types may be causing problems.  Too bad, because it allowed me to test [manually] with 8-bit numbers and easily change an implementation to 32- or 64-bit numbers (and I thought a common ancestor for all the natural numbers was more elegant, even if the work-arounds were not.)  I guess I can put the additional functionality in a utilities class.

Second, sorry my email changed.  I tried to update it but I never got an email response with an activation-code.  Maybe I can call.

Third, EiffelStudio 20.05 on my iMac keeps crashing, so I am still using the 19.05 version.

Fourth, I attached  a new archive_4.zip file which I believe has no externals and simplified ecf file;  It does (and must) use  the override files.

Now to the original problem, for what it is worth:
1)  The test routine 'is_negative' still violates the precondition "target_closed" in the call to `compare_functions' while other routines with the same pattern work just fine.
     a)  Well, not quite true now.  Feature `is_zero' now fails in same precondition when the program is run, but when executed by autoTest, it seems to work.   ???

2)  The test routine 'set_with_array' now mysteriously works.

See the attached "a_error_descripton.pdf" file describing the behavior as seen in the debugger.