lib/sewing_kit/webpack/dev.rb in sewing_kit-0.7.0 vs lib/sewing_kit/webpack/dev.rb in sewing_kit-0.7.1

@@ -1,7 +1,17 @@
 module SewingKit
   module Webpack
+    class NodeSewingKitNotInstalled < StandardError
+      def initialize()
+        super(
+          "sewing-kit is not available.  " +
+          "Please add `@shopify/sewing-kit` to package.json's `devDependencies`, " +
+          "and run  `yarn install`."
+        )
+      end
+    end
+
     class Dev
       attr_accessor :pid
 
       def start
         @pid = spawn
@@ -9,16 +19,19 @@
       end
 
       private
 
       def spawn
+        sewing_kit_bin = 'node_modules/.bin/sewing-kit'
+        raise NodeSewingKitNotInstalled.new unless File.exist?(sewing_kit_bin)
+
         Kernel.spawn(
           {
             'NODE_ENV' => 'development',
             'BLUEBIRD_DEBUG' => '0',
             'BLUEBIRD_LONG_STACK_TRACES' => '0',
           },
-          'node_modules/.bin/sewing-kit',
+          sewing_kit_bin,
           'dev',
           chdir: Rails.root.to_s,
           out: $stdout,
           err: $stderr,
         ) || exit(1)