FIX: user fields in invite signups were broken

app/assets/javascripts/discourse/controllers/invites-show.js.es6

@@ -61,7 +61,7 @@ export default Ember.Controller.extend(PasswordValidation, UsernameValidation, N
           username: this.get('accountUsername'),
           name: this.get('accountName'),
           password: this.get('accountPassword'),
-          userCustomFields
+          user_custom_fields: userCustomFields
         }
       }).then(result => {
         if (result.success) {

app/controllers/invites_controller.rb

@@ -31,7 +31,7 @@ class InvitesController < ApplicationController
 
   def perform_accept_invitation
     params.require(:id)
-    params.permit(:username, :name, :password, :user_custom_fields)
+    params.permit(:username, :name, :password, user_custom_fields: {})
     invite = Invite.find_by(invite_key: params[:id])
 
     if invite.present?