Improve error output when copying project fails

app/mailers/user_mailer.rb

@@ -115,9 +115,10 @@ class UserMailer < BaseMailer
     end
   end
 
-  def copy_project_failed(user, source_project, target_project_name)
+  def copy_project_failed(user, source_project, target_project_name, errors)
     @source_project = source_project
     @target_project_name = target_project_name
+    @errors = errors
 
     open_project_headers 'Source-Project' => source_project.identifier,
                          'Author'         => user.login

app/views/user_mailer/copy_project_failed.html.erb

@@ -30,3 +30,5 @@ See doc/COPYRIGHT.rdoc for more details.
 <h1><%= link_to @source_project.name, project_url(@source_project) %></h1>
 
 <%= t('copy_project.text.failed', source_project_name: @source_project.name, target_project_name: @target_project_name) %>
+
+<%= @errors.join("<br/>".html_safe) %>

app/views/user_mailer/copy_project_failed.text.erb

@@ -31,3 +31,5 @@ See doc/COPYRIGHT.rdoc for more details.
 <%= project_url(@source_project) %>
 
 <%= t('copy_project.text.failed', source_project_name: @source_project.name, target_project_name: @target_project_name) %>
+
+<%= @errors.join("\n") %>

app/workers/copy_project_job.rb

@@ -58,9 +58,9 @@ class CopyProjectJob < ApplicationJob
     if target_project
       UserMailer.copy_project_succeeded(user, source_project, target_project, errors).deliver_now
     else
-      target_project_name = target_project_params[:name]
+      target_project_name = target_project_params['name']
 
-      UserMailer.copy_project_failed(user, source_project, target_project_name).deliver_now
+      UserMailer.copy_project_failed(user, source_project, target_project_name, errors).deliver_now
     end
   end
 
@@ -106,6 +106,7 @@ class CopyProjectJob < ApplicationJob
       else
         errors         = target_project.errors.full_messages
         target_project = nil
+        logger.error("Copying project fails with validation errors: #{errors.join("\n")}")
       end
     end
   rescue ActiveRecord::RecordNotFound => e