fix: assets precompile by using terser

importmaps broke precompiliation with uglifier
see: https://github.com/rails/importmap-rails/issues/5

Gemfile

@@ -7,7 +7,6 @@ gem 'mail', '~> 2.7.1' # bug with mail 2.8.0 https://github.com/mikel/mail/issue
 
 gem 'sassc-rails'
 gem 'less-rails'
-gem 'uglifier'
 # See https://github.com/sstephenson/execjs#readme for more supported runtimes
 gem 'therubyracer', platforms: :ruby
 
@@ -128,3 +127,5 @@ group :test do
 end
 
 gem "importmap-rails", "~> 1.1"
+
+gem "terser", "~> 1.1"

Gemfile.lock

@@ -547,6 +547,8 @@ GEM
       sqlite3 (>= 1.3.3)
     table_print (1.5.7)
     temple (0.9.1)
+    terser (1.1.13)
+      execjs (>= 0.3.0, < 3)
     therubyracer (0.12.3)
       libv8 (~> 3.16.14.15)
       ref
@@ -567,8 +569,6 @@ GEM
       unf (~> 0.1.0)
     tzinfo (2.0.5)
       concurrent-ruby (~> 1.0)
-    uglifier (4.2.0)
-      execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.8.2)
@@ -683,9 +683,9 @@ DEPENDENCIES
   sprockets (< 4)
   sqlite3 (~> 1.3.6)
   table_print
+  terser (~> 1.1)
   therubyracer
   twitter-bootstrap-rails (~> 2.2.8)
-  uglifier
   web-console
   whenever
 

config/environments/production.rb

@@ -29,7 +29,7 @@ Rails.application.configure do
   config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?
 
   # Compress JavaScripts and CSS.
-  config.assets.js_compressor = :uglifier
+  config.assets.js_compressor = :terser
   config.assets.css_compressor = :sass
 
   # Do not fallback to assets pipeline if a precompiled asset is missed.