yarn install for engine.

Author: Mikhail Varabyou

lib/open_invoice/engine.rb

@@ -10,7 +10,12 @@ class Engine < ::Rails::Engine
 
     # add initializer for assets precompile
     initializer 'open_invoice.assets.precompile' do |app|
-      app.config.assets.paths << root.join('node_modules')
+      unless app.root.to_s.match root.to_s
+        app.config.assets.paths << root.join('node_modules')
+        Dir.chdir(root) do
+          `yarn install`
+        end
+      end
       app.config.assets.precompile += %w[open_invoice/application.css open_invoice/application.js]
     end