Find correct group membership.

app/controllers/projects_controller.rb

@@ -87,8 +87,7 @@ class ProjectsController < ApplicationController
             render 'projects/empty'
           else
             if current_user
-              @membership = @project.project_member_by_id(current_user.id)
-              @group_member = GroupMember.find_by(user_id: current_user.id)
+              @membership = @project.team.find_member(current_user.id)
             end
 
             render :show

app/views/projects/buttons/_notifications.html.haml

-- return unless [@membership, @group_member].any?
-
-- if @membership
+- case @membership
+- when ProjectMember
   = form_tag profile_notifications_path, method: :put, remote: true, class: 'inline', id: 'notification-form' do
     = hidden_field_tag :notification_type, 'project'
     = hidden_field_tag :notification_id, @membership.id
@@ -14,8 +13,8 @@
         - Notification.project_notification_levels.each do |level|
           = notification_list_item(level, @membership)
 
-- elsif @group_member
-  .btn.btn-new.disabled#notifications-button
+- when GroupMember
+  .btn.btn-new.disabled
     = icon('bell')
-    = notification_label(@group_member)
+    = notification_label(@membership)
     = icon('angle-down')