Updating the env when mutating without a join breaks the parser

[MrEbbinghaus]

When updating the env inside a mutation and not doing a join afterwards, the result of the mutation is returned without the removal of the ::p/env.

In the case of the parallel-parser with mutate-async this results in a StackOverflow when printing the result. (There is some sort of recursion happening in the data structure)

(pc/defmutation my-mutation [env _]
    {::pc/output []}
    {::p/env env})

(def p (p/parallel-parser {::p/mutate  pc/mutate-async
                                             ::p/env     {::p/reader [p/map-reader pc/parallel-reader]}
                                             ::p/plugins [(pc/connect-plugin {::pc/register [my-mutation]})]}))

(async/<!! (p {} `[(my-mutation {})]))
; => Error printing return value (StackOverflowError) ...
(async/<!! (p {} `[{(my-mutation {}) []}]))
; => {:my-mutation {}}

[souenzzo]

This is not a pathom issue
Using (set! *print-level* 3) should solve that

one sexp reproduce

(let [register [(pc/mutation `x1 {} (fn [env input]
                                      {::p/env env}))]
      parser (p/parallel-parser {::p/mutate  pc/mutate-async
                                 ::p/plugins [(pc/connect-plugin {::pc/register register})]})
      env {::p/reader [p/map-reader
                       pc/reader2
                       pc/open-ident-reader]}]
  (keys (async/<!! (parser env `[(x1)]))))