Fix error 'TypeError: Cannot read property 'snapshot' of undefined'

Author: FrankSalad

lib/modules/database/reference.js

@@ -126,7 +126,7 @@ export default class Reference extends ReferenceBase {
   transaction(transactionUpdate, onComplete, applyLocally) {
     const path = this._dbPath();
     return this.db.addTransaction(path, transactionUpdate, applyLocally)
-      .then(({ snapshot, committed }) => {snapshot: new Snapshot(this, snapshot), committed})
+      .then((({ snapshot, committed }) => {return {snapshot: new Snapshot(this, snapshot), committed}}).bind(this))
       .then(({ snapshot, committed }) => {
         if (isFunction(onComplete)) onComplete(null, snapshot);
         return {snapshot, committed};