Wait for transaction start to return to emit RxTransaction

Author: bigmontz

packages/neo4j-driver/src/session-rx.js

@@ -205,12 +205,15 @@ export default class RxSession {
 
     return new Observable(observer => {
       try {
-        observer.next(
-          new RxTransaction(
-            this._session._beginTransaction(accessMode, txConfig)
+        this._session._beginTransaction(accessMode, txConfig)
+          .then(transaction => observer.next(
+            new RxTransaction(
+              transaction
+            )
           )
-        )
-        observer.complete()
+          )
+          .then(() => observer.complete())
+          .catch(err => observer.error(err))
       } catch (err) {
         observer.error(err)
       }