can you see a fuller stacktrace?

yes

{:clojure.main/message
 x"Execution error (NoSuchMethodError) at com.google.javascript.jscomp.deps.ModuleLoader/createRootPaths (ModuleLoader.java:257).\n'java.util.stream.Collector com.google.common.collect.ImmutableSortedSet.toImmutableSortedSet(java.util.Comparator)'\n",
 :clojure.main/triage
 {:clojure.error/class java.lang.NoSuchMethodError,
  :clojure.error/line 257,
  :clojure.error/cause
  "'java.util.stream.Collector com.google.common.collect.ImmutableSortedSet.toImmutableSortedSet(java.util.Comparator)'",
  :clojure.error/symbol
  com.google.javascript.jscomp.deps.ModuleLoader/createRootPaths,
  :clojure.error/source "ModuleLoader.java",
  :clojure.error/phase :execution},
 :clojure.main/trace
 {:via
  [{:type java.lang.NoSuchMethodError,
    :message
    "'java.util.stream.Collector com.google.common.collect.ImmutableSortedSet.toImmutableSortedSet(java.util.Comparator)'",
    :at
    [com.google.javascript.jscomp.deps.ModuleLoader
     createRootPaths
     "ModuleLoader.java"
     257]}],
  :trace
  [[com.google.javascript.jscomp.deps.ModuleLoader
    createRootPaths
    "ModuleLoader.java"
    257]
   [com.google.javascript.jscomp.deps.ModuleLoader
    <init>
    "ModuleLoader.java"
    147]
   [com.google.javascript.jscomp.deps.ModuleLoader
    <init>
    "ModuleLoader.java"
    48]
   [com.google.javascript.jscomp.deps.ModuleLoader$Builder
    build
    "ModuleLoader.java"
    139]
   [com.google.javascript.jscomp.deps.ModuleLoader
    <clinit>
    "ModuleLoader.java"
    408]
   [com.google.javascript.jscomp.DiagnosticGroups
    <clinit>
    "DiagnosticGroups.java"
    189]
   [shadow.build.closure__init load nil 77]
   [shadow.build.closure__init <clinit> nil -1]
   [java.lang.Class forName0 "Class.java" -2]
   [java.lang.Class forName "Class.java" 398]

Just found out that this is the culprit.

(setq cider-jack-in-dependencies
      (delete-dups
       (append
        lispy-cider-jack-in-dependencies
        cider-jack-in-dependencies)))

I had added that because lispy tries to add pomegranate and dynapath dynamically but sometimes it fails. But seems like this is incompatible with cljs projects

funny thing, just this week we completed removing dynapath from cider-nrepl. what does lispy do to require such dynamism anyways? I don't know much about the project but good old paredit.el certainly never needs to inject JVM deps or such :)

https://github.com/abo-abo/lispy/blob/master/lispy-clojure.clj

Honestly all I care is the editing commands, so I think most of this somewhat unnecessary and better provided by cider and other modules

but I don't quite know how to disable it yet

Here you can track the logic it follows for conditionally injecting its stuff https://github.com/abo-abo/lispy/blob/e9731aa95581951ab2cbfaed28f0ac7d71124ac0/le-clojure.el#L145-L189 It observes (eq major-mode 'clojurescript-mode) . Maybe when you cider-jack-in-cljs the major mode is clojure-mode instead? You can also just setq lispy-cider-jack-in-dependencies nil , maybe that won't cause an immediate issue if you only use the editing commands

thanks for the suggestios, I'll try them out