Upgrade webpacker to ~> 4.0.0

Gemfile

@@ -4,8 +4,6 @@ source 'http://rubygems.org'
 
 ruby '2.5.5'
 
-
-gem 'webpacker', '~> 3.5'
 gem 'bootstrap-sass', '~> 3.3.7'
 gem 'bootstrap_form', '~> 2.7.0'
 gem 'devise', '~> 4.6.2'
@@ -102,6 +100,7 @@ gem 'newrelic_rpm'
 
 # Permission helper Gem
 gem 'canaid', git: 'https://github.com/biosistemika/canaid', branch: 'master'
+gem 'webpacker', '~> 4.0.0'
 
 group :development, :test do
   gem 'awesome_print'

Gemfile.lock

@@ -539,7 +539,7 @@ GEM
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
       hashdiff
-    webpacker (3.6.0)
+    webpacker (4.0.7)
       activesupport (>= 4.2)
       rack-proxy (>= 0.6.1)
       railties (>= 4.2)
@@ -657,7 +657,7 @@ DEPENDENCIES
   uglifier (>= 1.3.0)
   underscore-rails
   webmock
-  webpacker (~> 3.5)
+  webpacker (~> 4.0.0)
   whacamole
   wicked_pdf (~> 1.1.0)
   wkhtmltopdf-heroku

bin/webpack

@@ -12,4 +12,8 @@ require "bundler/setup"
 
 require "webpacker"
 require "webpacker/webpack_runner"
-Webpacker::WebpackRunner.run(ARGV)
+
+APP_ROOT = File.expand_path("..", __dir__)
+Dir.chdir(APP_ROOT) do
+  Webpacker::WebpackRunner.run(ARGV)
+end

bin/webpack-dev-server

@@ -12,4 +12,8 @@ require "bundler/setup"
 
 require "webpacker"
 require "webpacker/dev_server_runner"
-Webpacker::DevServerRunner.run(ARGV)
+
+APP_ROOT = File.expand_path("..", __dir__)
+Dir.chdir(APP_ROOT) do
+  Webpacker::DevServerRunner.run(ARGV)
+end

package.json

@@ -39,10 +39,10 @@
     "flow-typed": "^2.5.1",
     "prettier": "^1.13.7",
     "prettier-eslint": "^8.8.2",
-    "webpack-dev-server": "^2.11.2"
+    "webpack-dev-server": "^3.7.2"
   },
   "dependencies": {
-    "@rails/webpacker": "^3.5.5",
+    "@rails/webpacker": "^4.0.7",
     "autoprefixer": "^7.2.6",
     "axios": "0.18.1",
     "babel-core": "^6.26.3",