BHV-12189: Fix missing assignment on Async.js

Adding missed condition check and assignment to support backward compatibility.

DCO-1.1-Signed-Off-By: Kunmyon Choi kunmyon.choi@lge.com
Merge pull request #815 from enyojs/BHV-12189-kunmyonchoi-master

BHV-12189: Fix missing assignment on Async.js

Reviewed-By: Cole Davis (cole.davis@lge.com)