Created attachment 1120803 [details]
Web console log, engine.log and a screenshot

Description of problem:
I got a "Uncaught exception occurred" error message in UI for destroying a storage domain.

Version-Release number of selected component (if applicable):
rhevm-3.6.3-0.1.el6.noarch

How reproducible:
Always

Steps to Reproduce:
1. Have an unattached storage domain
2. Destroy the domain


Actual results:
Destroy storage domain raises the mentioned exception in UI. From console log (firefox):

"Wed Feb 03 16:35:26 GMT+200 2016 
SEVERE: Uncaught exception: com.google.gwt.core.client.JavaScriptException: (TypeError) 
 __gwt$exception: <skipped>: c is null
	at Unknown.ezq(Unknown Source)
	at Unknown.tPn(Unknown Source)
	at Unknown.wPn(Unknown Source)
	at Unknown.nTn(Unknown Source)
	at Unknown.qTn(Unknown Source)
	at Unknown.lSn(Unknown Source)
	at Unknown.oSn(Unknown Source)
	at Unknown.UIe(Unknown Source)
	at Unknown._xk(Unknown Source)
	at Unknown.v3(Unknown Source)
	at Unknown.O3(Unknown Source)
	at Unknown.Svf/c.onreadystatechange<(Unknown Source)
	at Unknown.Yt(Unknown Source)
	at Unknown.au(Unknown Source)
	at Unknown._t/<(Unknown Source)
	at Unknown.anonymous(Unknown Source)

Expected results:
Storage domain destroy shouldn't invoke this exception.

Additional info:
Web console log, engine.log and a screenshot