FIX: Minor bugfixes in manager and create_group action

controllers/custom_wizard/admin/manager.rb

@@ -48,20 +48,21 @@ class CustomWizard::AdminManagerController < CustomWizard::AdminController
 
     imported = []
     failures = []
+    templates = template_json.is_a?(Array) ? template_json : [template_json]
 
-    template_json.each do |json|
-      template = CustomWizard::Template.new(json)
+    templates.each do |raw_template|
+      template = CustomWizard::Template.new(raw_template)
       template.save(skip_jobs: true, create: true)
 
       if template.errors.any?
         failures.push(
-          id: json['id'],
+          id: template.data['id'],
           messages: template.errors.full_messages.join(', ')
         )
       else
         imported.push(
-          id: json['id'],
-          name: json['name']
+          id: template.data['id'],
+          name: template.data['name']
         )
       end
     end

lib/custom_wizard/mapper.rb

@@ -225,7 +225,7 @@ class CustomWizard::Mapper
   end
 
   def interpolate(string, opts = { user: true, wizard: true, value: true, template: false })
-    return string if string.blank?
+    return string if string.blank? || string.frozen?
 
     if opts[:user]
       string.gsub!(/u\{(.*?)\}/) { |match| map_user_field($1) || '' }