Enhance foreign key detection

src/utils.js

@@ -50,11 +50,15 @@ function getRemovable(db) {
       _(doc).each(function(value, key) {
         if (/Id$/.test(key)) {
           var refName = _.pluralize(key.slice(0, - 2))
+          // Test if table exists
+          if (db[refName]) {
+            // Test if references is defined in table
             var ref = _.findWhere(db[refName], {id: value})
             if (_.isUndefined(ref)) {
               removable.push({ name: collName, id: doc.id })
             }
           }
+        }
       })
     })
   })