Using clearer json_request? method for customers controller

app/controllers/admin/customers_controller.rb

@@ -17,7 +17,7 @@ module Admin
     private
 
     def collection
-      return Customer.where("1=0") if html_request? || params[:enterprise_id].nil?
+      return Customer.where("1=0") unless json_request? && params[:enterprise_id].present?
       enterprise = Enterprise.managed_by(spree_current_user).find_by_id(params[:enterprise_id])
       Customer.of(enterprise)
     end

app/controllers/spree/admin/base_controller_decorator.rb

@@ -62,4 +62,8 @@ Spree::Admin::BaseController.class_eval do
   def html_request?
     request.format.html?
   end
+
+  def json_request?
+    request.format.json?
+  end
 end