Disallow EJSON custom types as replacement documents in updates

packages/mongo/mongo_driver.js

@@ -320,7 +320,7 @@ MongoConnection.prototype._insert = function (collection_name, document,
   if (!(LocalCollection._isPlainObject(document) &&
         !EJSON._isCustomType(document))) {
     sendError(new Error(
-      "Only documents (plain objects) may be inserted into MongoDB"));
+      "Only plain objects may be inserted into MongoDB"));
     return;
   }
 
@@ -432,6 +432,14 @@ MongoConnection.prototype._update = function (collection_name, selector, mod,
   if (!mod || typeof mod !== 'object')
     throw new Error("Invalid modifier. Modifier must be an object.");
 
+  if (!(LocalCollection._isPlainObject(mod) &&
+        !EJSON._isCustomType(mod))) {
+    throw new Error(
+      "Only plain objects may be used as replacement" +
+        " documents in MongoDB");
+    return;
+  }
+
   if (!options) options = {};
 
   var write = self._maybeBeginWrite();

packages/mongo/mongo_livedata_tests.js

@@ -1481,6 +1481,7 @@ testAsyncMulti('mongo-livedata - document with a custom type, ' + idGeneration,
       test.isFalse(err);
       test.isTrue(id);
       docId = id;
+      self.docId = docId;
       var cursor = self.coll.find();
       test.equal(cursor.count(), 1);
       var inColl = self.coll.findOne();
@@ -1493,6 +1494,12 @@ testAsyncMulti('mongo-livedata - document with a custom type, ' + idGeneration,
       test.isTrue(err);
       test.isFalse(id);
     }));
+  }, function (test, expect) {
+    var self = this;
+    self.coll.update(
+      self.docId, new Dog("rover", "orange"), expect(function (err) {
+        test.isTrue(err);
+      }));
   }
 ]);