Handle possible strict mode bugs (#4106)

Co-authored-by: Ben Broderick Phillips <bebroder@microsoft.com>

eng/common/scripts/stress-testing/stress-test-deployment-lib.ps1

@@ -56,7 +56,7 @@ function Login([string]$subscription, [string]$clusterGroup, [switch]$pushImages
     $kubeContext = (RunOrExitOnFailure kubectl config view -o json) | ConvertFrom-Json -AsHashtable
     $defaultNamespace = $null
     $targetContext = $kubeContext.contexts.Where({ $_.name -eq $clusterName }) | Select -First 1
-    if ($targetContext -ne $null) {
+    if ($targetContext -ne $null -and $targetContext.PSObject.Properties.Name -match "namespace") {
         $defaultNamespace = $targetContext.context.namespace
     }