If the SSH client process that PowerShell is using for the SSH transport terminates abruptly the StreamReader will return null instead of closing the pipe for a normal process exit.

The current error stream reading code ignores null StreamReader values resulting in a hang where the remote session never ends.

Steps to reproduce

PS > New-PSSession -HostName <cnName>
PS > Get-Process SSH | kill -force

Expected behavior

Session state goes to "Broken" with error message

Actual behavior

Session is broken and hangs on the client end

Environment data

Current build