Passing proper error object back from mapreduce method

Author: christkv

lib/mongodb/admin.js

@@ -12,10 +12,11 @@ Admin.prototype.serverInfo = function(callback) {
   var databaseName = self.db.databaseName;
   self.db.databaseName = 'admin';
   this.db.executeDbCommand(command, function(err, doc) {
-    self.db.databaseName = databaseName;
     if(err != null) return callback(err, null);
     return callback(null, doc.documents[0]);
   });
+  // Ensure change before event loop executes
+  self.db.databaseName = databaseName;
 }
 
 Admin.prototype.profilingLevel = function(callback) {

lib/mongodb/collection.js

@@ -512,7 +512,7 @@ Collection.prototype.mapReduce = function(map, reduce, options, callback) {
         }
       });
     } else {
-      err != null ? callback(err, null, null) : callback(new Error("map-reduce failed: " + result.documents[0].errmsg), null, null);
+      err != null ? callback(err, null, null) : callback(result.documents[0], null, null);
     }
   });
 };