No Returning value in PowerShell after adding nslookup command

After adding the code

$ip = (nslookup $pcName | Select-String Address | Where-Object LineNumber -eq 5).ToString().Split(' ')[-1]

It will not give any result when the user has NO pc name assigned to his User ID. The script doesn't run and it's giving a blank result. It works when the user has a PC name assigned to his user id.

The same when the user ID cannot be found due to typo or something else. There I want to prompt the user to give in the correct user ID and restart the script. I'm trying to figure it out how it can be done but I don't find the correct way to do it.

Thanks in advance for your help!

$csv = Import-CSV 'C:\Users\ADMIN\Desktop\Powershells\Computers in a specific workgroup or domain.csv'
$ADprops = @(
    'DisplayName'
    'Mail'
    'LastBadPasswordAttempt'
    'AccountExpirationDate'
    'PasswordLastSet'
)

$filter = @(
    $ADprops
    @{ 
        Name = 'Password Changeable'
        Expression = { $changeable }
    }, @{
        Name = 'Password Expires'
        Expression = { $expires }
    }, @{
        Name = 'Last logon'
        Expression = { $lastlogon }
    }, @{
        Name = 'PC Name'
        Expression = { $pcName }
    }, @{   
        Name = 'Address'
        Expression = { $ip }
    }

)

Clear-Host
do
{
    Write-Host " Enter the user ID: " -ForegroundColor Cyan -NoNewline
    $UserName = Read-Host
    Write-Host ""

    $pcName = $csv.Where({ $_."User ID" -match $Username })."PC Name"
    $ip = (nslookup $pcName | Select-String Address | Where-Object LineNumber -eq 5).ToString().Split(' ')[-1]
    $expires, $changeable = net user $Username /domain |
    Select-String -Pattern 'Password Changeable|Password Expires|Last logon'|
    ForEach-Object { ($_ -split '\s{2,}')[1] }
    Get-ADUser -Identity $Username -Properties $ADprops |
    Select-Object $filter

} while ($Username -notcontains $Processes)

When testing your code I notice that when you provide the function nsloockup with empty string value the function is stucked. What I suggest is to add a check on the $pcName variable as follow:

$pcName = $csv.Where({ $_."User ID" -match $Username })."PC Name"
if([string]::IsNullOrEmpty($pcName)){
    continue;
}