"lein ring uberwar" throws NPE in asset-minifier

Question

I created a new Reagent project with lein new reagent, and then added a bunch of code to it, and it all works fine locally. Then I tried to package it up with lein ring uberwar for deployment, and that command throws a NullPointerException.

I updated all the libraries in my project.clj to their latest versions.

The issue looks very much like this, but yogthos says it's not an issue with that library, and I can confirm that a new Reagent project (plus [lein-ring "0.12.5"]) generates an uberwar just fine.

I haven't touched any of the asset-minimizer (or uberwar) parts of the default project.clj file:

  :minify-assets
  {:assets
   {"resources/public/css/site.min.css" "resources/public/css/site.css"}}

(where this site.css is an empty file)

and in :profiles:

             :uberjar {:hooks [minify-assets.plugin/hooks]
                       :source-paths ["env/prod/clj"]
                       :prep-tasks ["compile" ["cljsbuild" "once" "min"]]
                       :env {:production true}
                       :aot :all
                       :omit-source true}})

When I run the uberwar command, I see:

$ lein ring uberwar

minifying assets...
java.lang.NullPointerException: null
 at leiningen.minify_assets$normalize_path.invokeStatic (minify_assets.clj:78)
    leiningen.minify_assets$normalize_path.invoke (minify_assets.clj:74)
    leiningen.minify_assets$normalize_assets$iter__11627__11631$fn__11632.invoke (minify_assets.clj:83)
    clojure.lang.LazySeq.sval (LazySeq.java:40)
    clojure.lang.LazySeq.seq (LazySeq.java:49)
    clojure.lang.RT.seq (RT.java:521)
    clojure.core$seq__4357.invokeStatic (core.clj:137)
    clojure.core/seq (core.clj:137)
    clojure.spec.alpha$every_impl$reify__2751.conform_STAR_ (alpha.clj:1244)
    clojure.spec.alpha$valid_QMARK_.invokeStatic (alpha.clj:756)
    clojure.spec.alpha$valid_QMARK_.invoke (alpha.clj:752)
    asset_minifier.spec$is_valid_config.invokeStatic (spec.clj:17)
    asset_minifier.spec$is_valid_config.invoke (spec.clj:16)
    asset_minifier.core$minify.invokeStatic (core.clj:214)
    asset_minifier.core$minify.invoke (core.clj:208)
    leiningen.minify_assets$minify.invokeStatic (minify_assets.clj:18)
    leiningen.minify_assets$minify.invoke (minify_assets.clj:16)
    leiningen.minify_assets$run_assets_minify.invokeStatic (minify_assets.clj:95)
    leiningen.minify_assets$run_assets_minify.invoke (minify_assets.clj:94)
    leiningen.minify_assets$minify_assets.invokeStatic (minify_assets.clj:103)
    leiningen.minify_assets$minify_assets.doInvoke (minify_assets.clj:97)
    clojure.lang.RestFn.invoke (RestFn.java:410)
    minify_assets.plugin$add_minify_assets_hook.invokeStatic (plugin.clj:8)
    minify_assets.plugin$add_minify_assets_hook.doInvoke (plugin.clj:6)

(and then dozens more lines of generic-looking Clojure call stack that don't mention asset-minifier)

How would I go about tracking down what is causing this NPE?

Answer 1

The NPE is thrown because path of the assets, which is specified in :minify-assets ,can not be parsed correctly. (see this).

IMO, :minify-assets is not defined correctly. Due to the Readme the :minify-assets should look like this:

:minify-assets [[:html {:source "dev/resource/html" :target "dev/minified/html"}]
                [:css {:source "dev/resources/css" :target "dev/minified/css/styles.min.css"}]
                [:js {:source ["dev/res/js1", "dev/res/js2"] :target "dev/minified/js/script.min.js"}]]