Unable to load the core Node.js libraries using cider/figwheel.

[FieryCod]

Step to reproduce:

1. Clone https://github.com/FieryCod/core-library-require-minimal-repro
2. Use cider figwheel
3. cider-eval-last-sexp on ns form

Error: Figwheel: message from client couldn't be read! Eval timed out! No stacktrace available.

Stacktrace:

1. Unhandled clojure.lang.ExceptionInfo
   Eval timed out!
   {:type :js-eval-exception,
    :error
    {:status :exception,
     :value "Eval timed out!",
     :stacktrace "No stacktrace available."},
    :form (ns figwheel-node-req-repro.core (:require fs)),
    :js
    "goog.provide('figwheel_node_req_repro.core');\ngoog.require('cljs.core');\nfigwheel_node_req_repro.core.node$module$fs = require('fs');\n"}

                  core.clj: 4739  clojure.core/ex-info
                  core.clj: 4739  clojure.core/ex-info
                 repl.cljc:  577  cljs.repl$evaluate_form/invokeStatic
                 repl.cljc:  498  cljs.repl$evaluate_form/invoke
            piggieback.clj:  209  cider.piggieback/eval-cljs
            piggieback.clj:  208  cider.piggieback/eval-cljs
            piggieback.clj:  235  cider.piggieback/do-eval
            piggieback.clj:  216  cider.piggieback/do-eval
            piggieback.clj:  258  cider.piggieback/evaluate
            piggieback.clj:  256  cider.piggieback/evaluate
                  Var.java:  381  clojure.lang.Var/invoke
            piggieback.clj:  287  cider.piggieback/wrap-cljs-repl/fn/fn/fn
            piggieback.clj:  191  cider.piggieback/enqueue/fn
    interruptible_eval.clj:  190  clojure.tools.nrepl.middleware.interruptible-eval/run-next/fn
                  AFn.java:   22  clojure.lang.AFn/run
   ThreadPoolExecutor.java: 1149  java.util.concurrent.ThreadPoolExecutor/runWorker
   ThreadPoolExecutor.java:  624  java.util.concurrent.ThreadPoolExecutor$Worker/run
               Thread.java:  748  java.lang.Thread/run

When trying to evaluate the whole buffer then the evaluation succeeds.

Everything works as it should using the figwheel-main.

[FieryCod]

/Users/karol/workspace/clojure/lein-figwheel/sidecar/src/figwheel_sidecar/components/figwheel_server.clj 

read-msg method receives something like {:value {#js {:prop1 blabla}} when using cider-eval-last-sexp. Therefore parsing that string returns an error. What I think is that I should just regexp the string and remove #js. What do you think @bhauman?

EDIT: This is what read-msg method really receives

"{:figwheel-event "callback", :callback-name "figwheel_callback_37403", :content {:status :success, :out "", :ua-product :chrome, :value #js {:_toBuf #object[toBuf], :createCipher #object[createCipher], :createCipheriv #object[createCipheriv], :createDecipher #object[createDecipher], :createDecipheriv #object[createDecipheriv], :createDiffieHellman #object[createDiffieHellman], :createDiffieHellmanGroup #object[createDiffieHellmanGroup], :createECDH #object[createECDH], :createHash #object[createHash], :createHmac #object[createHmac], :createSign #object[createSign], :createVerify #object[createVerify], :getCiphers #object[Function], :getCurves #object[Function], :getDiffieHellman #object[createDiffieHellmanGroup], :getHashes #object[Function], :pbkdf2 #object[pbkdf2], :pbkdf2Sync #object[pbkdf2Sync], :privateDecrypt #object[Function], :privateEncrypt #object[Function], :prng #object[randomBytes], :pseudoRandomBytes #object[randomBytes], :publicDecrypt #object[Function], :publicEncrypt #object[Function], :randomBytes #object[randomBytes], :randomFill #object[randomFill], :randomFillSync #object[randomFillSync], :rng #object[randomBytes], :setEngine #object[setEngine], :timingSafeEqual #object[timingSafeEqual], :Certificate #object[Certificate], :Cipher #object[Cipher], :Cipheriv #object[Cipheriv], :Decipher #object[Decipher], :Decipheriv #object[Decipheriv], :DiffieHellman #object[DiffieHellman], :DiffieHellmanGroup #object[DiffieHellmanGroup], :ECDH #object[ECDH], :Hash #object[Hash], :Hmac #object[Hmac], :Sign #object[Sign], :Verify #object[Verify], :DEFAULT_ENCODING "buffer", :constants #object[Object], :createCredentials #object[createSecureContext], :Credentials #object[SecureContext]}}}"

[bhauman]

Splitting on the #js is unfortunately not a solution to consider here. Reading errors need to be fixed by changing the reader so that it reads better.

And I'm not sure this is a reading error neccessarily because figwheel.main has the exact same code for reading responses from the client.

[FieryCod]

read-msg is not a reader stuff?

(defn- replace-unparsable-js
  "Replaces #js in msg with 'nil to avoid read error when importing built-in Node.js libraries (CLJS 1.10)"
  [msg]
  (string/replace msg #"(#js \{[:#\w\[\]\", ]*\})" "nil"))

(defn read-msg [data]
  (try
    (println (replace-unparsable-js data))
    (let [msg (edn/read-string (replace-unparsable-js data))]
      (if (and (map? msg) (:figwheel-event msg))
        msg
        {}))
    (catch Exception e
      (println "Figwheel: message from client couldn't be read!")
      {})))

This is what solves the problem. If it doesn't satisfy you please point me where in code should I look for the problem.