Fix requests for deleted users

When users are requested from the authorship which no longer exist, they
shouldn't cause a 500.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

lib/models/user.js

@@ -66,6 +66,9 @@ module.exports = function (sequelize, DataTypes) {
         })
       },
       getProfile: function (user) {
+        if (!user) {
+          return null
+        }
         return user.profile ? User.parseProfile(user.profile) : (user.email ? User.parseProfileByEmail(user.email) : null)
       },
       parseProfile: function (profile) {