I think you should be able to get rid of the is-oil part, because set -E was implemented last year

    $ osh -c 'set -E; set -o |grep errtrace'
    set -o errtrace

I'd be interested in any bug reports if it doesn't behave the same way

(The Oils runtime supports FUNCNAME BASH_SOURCE and all that, but there is room for a much better introspection API. It actually has a JSON crash report with a shell stack dump, but it probably needs some polish.)