Fixed error when no OAuth application is associated with GeoNode.

app/controllers/oauth/geo_auth_controller.rb

@@ -35,7 +35,7 @@ class Oauth::GeoAuthController < ActionController::Base
   private
 
   def undefined_oauth_application
-    @error = 'There is no OAuth application defined for this Geo node.'
+    @error = 'There are no OAuth application defined for this Geo node. Please ask your administrator to visit "Geo Nodes" on admin screen and click on "Repair authentication".'
     render :error, layout: 'errors'
   end
 end

lib/gitlab/geo.rb

@@ -46,7 +46,7 @@ module Gitlab
       return false unless Gitlab::Geo.secondary?
 
       RequestStore.store[:geo_oauth_application] ||= Gitlab::Geo.current_node.oauth_application or
-                                                     raise GeoOauthApplicationUndefinedError
+                                                     raise OauthApplicationUndefinedError
     end
   end
 end