Fix mailer to use webpack core

app/javascript/core/mailer.js

@@ -0,0 +1 @@
+import 'styles/mailers.scss';

app/javascript/core/theme.yml

@@ -10,6 +10,9 @@ pack:
   embed: embed.js
   error:
   home:
+  mailer:
+    filename: mailer.js
+    stylesheet: true
   modal:
   public: public.js
   settings: settings.js

app/javascript/flavours/glitch/theme.yml

@@ -15,6 +15,7 @@ pack:
     - flavours/glitch/async/getting_started
     - flavours/glitch/async/home_timeline
     - flavours/glitch/async/notifications
+  mailer:
   modal:
   public: packs/public.js
   settings:

app/javascript/flavours/vanilla/theme.yml

@@ -15,6 +15,7 @@ pack:
     - features/compose
     - features/home_timeline
     - features/notifications
+  mailer:
   modal:
   public: public.js
   settings:

app/javascript/packs/mailer.js

@@ -1 +0,0 @@
-require('../styles/mailer.scss');