Example in code -
(conj {} [:something "something" :dark "side"]) -- Fails
(conj {} [:something "something"]) -- Succeeds
The second conj succeeds and reveals why this can be masked, passing a vector with 2 elements into the conj of a map will succeed.
Example when using lein-js
(defproject myexample "1.0.0-SNAPSHOT"
:js { :prod-options [:process-closure-primitives true
:compilation-level :advanced-optimizations]})
should be
(defproject myexample "1.0.0-SNAPSHOT"
:js { :prod-options {:process-closure-primitives true
:compilation-level :advanced-optimizations}})