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/realtime.js

@@ -486,11 +486,13 @@ function startConnection (socket) {
       for (var i = 0; i < note.authors.length; i++) {
         var author = note.authors[i]
         var profile = models.User.getProfile(author.user)
-        authors[author.userId] = {
-          userid: author.userId,
-          color: author.color,
-          photo: profile.photo,
-          name: profile.name
+        if (profile) {
+          authors[author.userId] = {
+            userid: author.userId,
+            color: author.color,
+            photo: profile.photo,
+            name: profile.name
+          }
         }
       }