Calling our basis function with just :oss or :ee we don't end up with an
`:argmap` key.

```clojure
uberjar=> (def basis (create-basis :oss))
,#'build.uberjar/basis
uberjar=> (:argmap basis)
nil          ;; nothing extra in oss

uberjar=> (def basis (create-basis :ee))
,#'build.uberjar/basis
uberjar=> (:argmap basis)
{:extra-paths ["enterprise/backend/src"]}

;; and if other aliases are used:
uberjar=> (def basis' (b/create-basis {:project "deps.edn" :aliases [:dev :test]}))
,#'build.uberjar/basis'
uberjar=> (:argmap basis')
{:extra-deps {lambdaisland/deep-diff2 {:mvn/version "2.7.169"},
              methodical/methodical {:mvn/version "0.15.1"},
              io.github.metabase/hawk {:sha
              "45ed36008014f9ac1ea66beb56fb1c4c39f8342b"},
              ....}
 :extra-paths ["dev/src"...]
 :jvm-opts ["-Dmb.run.mode=dev" ...]
 :exec-fn metabase.test-runner/find-and-run-tests-cli}
```