Fix exception when epic has no author

Failure to assign the ghost author or delete epic when a user is
deleted with contributions has left some with no author. This
causes the Epic List to break as it tries to link to an author
that isn't there. This fixes the link_to_member method to handle
a missing author so at least this page will load.

Changelog: fixed

app/helpers/projects_helper.rb

@@ -54,14 +54,14 @@ module ProjectsHelper
     default_opts = { avatar: true, name: true, title: ":name" }
     opts = default_opts.merge(opts)
 
+    return "(deleted)" unless author
+
     data_attrs = {
       user_id: author.id,
       username: author.username,
       name: author.name
     }
 
-    return "(deleted)" unless author
-
     author_html = []
 
     # Build avatar image tag

spec/helpers/projects_helper_spec.rb

@@ -345,6 +345,14 @@ RSpec.describe ProjectsHelper do
         expect(link).not_to include(user.name)
       end
     end
+
+    context 'when user is nil' do
+      it 'returns "(deleted)"' do
+        link = helper.link_to_member(project, nil)
+
+        expect(link).to eq("(deleted)")
+      end
+    end
   end
 
   describe 'default_clone_protocol' do