Handle exit by promisifying lumo compilation

This patch fixes the fact that serverless could not display the failures of
compilation in lumo. It also needs the very latest lumo for it to work.

README.md

@@ -40,9 +40,11 @@ In the example above, there needn't be a corresponding entry for `echo` in
 
 ## Lumo
 
-Alternatively you can use the [Lumo](https://github.com/anmonteiro/lumo)
+Alternatively, you can use the [Lumo](https://github.com/anmonteiro/lumo)
 [compiler](https://anmonteiro.com/2017/02/compiling-clojurescript-projects-without-the-jvm/).
 
+Note that `serverless-cljs-plugin` needs _Lumo >= 1.8.0_.
+
 In order to enable it, pass the `--lumo` switch to either `deploy` or `package`:
 
 ```shell

serverless-cljs-plugin/serverless_lumo/build.cljs

@@ -4,7 +4,7 @@
             [cljs.reader :as reader]
             [lumo.build.api]
             [lumo.classpath :as classpath]
-            [lumo.core]
+            [lumo.core :as lumo]
             [lumo.io :as io]
             [serverless-lumo.index :as index]))
 
@@ -51,9 +51,16 @@
    "Invoking the Lumo compiler w/ inputs"
    (.stringify js/JSON (clj->js inputs)))
   (run! classpath/add! inputs)
-  (lumo.build.api/build
-   (apply lumo.build.api/inputs inputs)
-   compiler-opts))
+
+  (js/Promise.
+   (fn [resolve reject]
+     (lumo.build.api/build
+      (apply lumo.build.api/inputs inputs)
+      compiler-opts
+      (fn [result]
+        (if (:error result)
+          (reject result)
+          (resolve result)))))))
 
 (defn read-conf!
   "Read and return the configuration map."
@@ -69,7 +76,6 @@
   {:source-paths ["src"]
    :compiler     {:output-to     (.format path #js {:dir "out" :base "lambda.js"})
                   :output-dir    "out"
-                  :source-map    false ;; lumo bug
                   :target        :nodejs
                   :optimizations :none}})
 
@@ -94,11 +100,11 @@
       (dump-index! (.resolve path output-dir "../index.js")
                    (:functions opts)
                    compiler))
-    (compile! (:source-paths cljs-lambda-opts) compiler)
-    (zip! (:zip-path opts)
-          {:dirs  #{output-dir "node_modules"}
-           :files #{[index {:name "index.js"}]}}
-          compiler)))
+    (.then (compile! (:source-paths cljs-lambda-opts) compiler)
+           #(zip! (:zip-path opts)
+                  {:dirs  #{output-dir "node_modules"}
+                   :files #{[index {:name "index.js"}]}}
+                  compiler))))
 
 (def cli-option-map
   {:z :zip-path
@@ -134,6 +140,8 @@
 
 (defn ^:export -main [& args]
   (let [opts (cli-options (cmd-line-args))]
-    (build! opts (merge-maps default-config (read-conf!)))))
+    (.then (build! opts (merge-maps default-config (read-conf!)))
+           lumo/exit
+           #(lumo/exit 2))))
 
 (set! *main-cli-fn* -main)