webapp: Stop executing if an exception is thrown when adding a custom domain to a website.

[jocawtho]

Description

When a user makes a mistake in their powershell script. It sometimes results in all their existing custom domains being removed. As part of the WebsiteClient in chaning customDomains the client does a GET to see existing domains, adds new domains, and then Deletes domains that are not included. If a customDomain fails to be added, we should not remove custom domains and should stop that part of the update customDomains code.

Steps to reproduce

I understand that this isnt the newest version, but I forgot to save those commands

$W=Get-AzureRmWebApp -ResourceGroupName "prod-rg" -Name "prod-rg"
$X = $W.hostnames
$X.add("mycustom.domain.com")
$HN = $X.tostring()
Set-AzureRmWebApp -ResourceGroupName "prod-rg" -Name "prod-rg" -HostNames  $HN

At this point, X = [oldDomain1, OldDomain2, New domain]
And HN = system.collections.generic.list`1[system.string]
When customer tries to send HN the websites cmdlet sends that one new domain, this fails because this 'domain' is not valid. and then the websites cmdlet continues

Environment data

Module versions

Debug output

Error output

[ThejaChoudary]

Taking a look at this..