Merge pull request rails#232 from aganov/fix/webpacker-check-node

Fix nodejs and yarn checks

lib/tasks/webpacker/check_node.rake

@@ -3,8 +3,11 @@ namespace :webpacker do
   task :check_node do
     begin
       node_version = `node -v`
-      if node_version.tr("v", "").to_f < 6.4
-        puts "Webpacker requires Node.js >= 6.4 and you are using #{node_version}"
+      required_node_version = "6.4"
+
+      raise Errno::ENOENT if node_version.blank?
+      if Gem::Version.new(node_version.strip.tr("v", "")) < Gem::Version.new(required_node_version)
+        puts "Webpacker requires Node.js >= v#{required_node_version} and you are using #{node_version}"
         puts "Please upgrade Node.js https://nodejs.org/en/download/"
         puts "Exiting!" && exit!
       end

lib/tasks/webpacker/check_yarn.rake

@@ -2,7 +2,8 @@ namespace :webpacker do
   desc "Verifies if yarn is installed"
   task :check_yarn do
     begin
-      `yarn --version`
+      version = `yarn --version`
+      raise Errno::ENOENT if version.blank?
     rescue Errno::ENOENT
       puts "Webpacker requires yarn. Please download and install Yarn https://yarnpkg.com/lang/en/docs/install/"
       puts "Exiting!" && exit!