Merge pull request #278 from derbyjs/doc-unload-fix

Be more defensive for delayed doc unload introduced in a320772

Author: ericyhwang

lib/Model/subscriptions.js

@@ -190,7 +190,7 @@ Model.prototype._maybeUnloadDoc = function(collectionName, id) {
     var previous = doc.get();
 
     // Remove doc from Racer
-    model.root.collections[collectionName].remove(id);
+    if (model.root.collections[collectionName]) model.root.collections[collectionName].remove(id);
     // Remove doc from Share
     if (doc.shareDoc) doc.shareDoc.destroy();