Create menu tabs with views
This is a known issue in views.

The issue is that the route parameter for entities needs to be named:


  This view will be displayed by visiting this path on your site. You
  may use "%" or named route parameters like "%node" in your URL to
  represent values that will be used for contextual filters: For
  example, "node/%node/feed" or "view_path/%". The named route
  parameters are necessary when used within paths used by entities such
  as "taxonomy/term/%taxonomy_term" or "user/%user/custom-view


This is for the first error message. 

The second one is caused by the devel module. If you still get this error after renaming the route parameter, you have to check the issue queue from this module.