Fix folders exports, add error message

SCI-5351

app/assets/javascripts/projects/index.js

@@ -180,8 +180,8 @@
           // Show the modal
           exportProjectsModal.modal('show');
         },
-        error: function() {
-          // TODO
+        error: function(data) {
+          HelperModule.flashAlertMsg(data.responseJSON.flash, 'danger');
         }
       });
     });

app/controllers/teams_controller.rb

@@ -65,6 +65,8 @@ class TeamsController < ApplicationController
           status: 'error'
         }
       end
+    else
+      render json: { flash: I18n.t('projects.export_projects.zero_projects_flash') }, status: :unprocessable_entity
     end
   end
 

app/models/project_folder.rb

@@ -87,9 +87,7 @@ class ProjectFolder < ApplicationRecord
   end
 
   def inner_projects
-    project_folders.map do |inner_folder|
-      projects + inner_folder.inner_projects
-    end.flatten
+    Project.where(project_folder: ProjectFolder.inner_folders(team, self) + [self])
   end
 
   private

config/locales/en.yml

@@ -460,6 +460,7 @@ en:
       modal_text_p3_html: "Please note that the number of exports is limited to %{limit} requests per day. After you confirm this export you will have %{num} left."
       modal_submit: "Export"
       success_flash: "Export request received. Your export request is being processed."
+      zero_projects_flash: "You have to select at least one project"
     activity:
       visibility_hidden: "Project members only"
       visibility_visible: "All team members"