Try..ing

try
{
    Add-PSSnapin "Citrix*"
    function ServerOnline{
        $server = $args[0] # Create a variable named server from the first passed variable
        $isregistered = @(get-brokermachine $server -RegistrationState "Registered")
        foreach ($result in $isregistered){
            return $true}}
}
catch
{
    if ($EnableSMTP -eq $true){$SMTPClient.Send($EmailFrom, $EmailTo, "Unhandled error has occurred in main program: " + $error[0], "")}
    $EventLog.WriteEntry("Unhandled error has occurred in main program: " + $error[0],"Information") # Brute force error handling method to catch all errors
}