Powershell WebScraping and Terminating Exception Handling - powershell

Question

I'm using powershell to check several different sites for data. If the site has no data for today, it will throw a NullReferenceException. I'd like for the script to output a message that there is no data, then continue on to the other sites without halting.
In Java, I can simply just try/catch/finally, but Powershell isn't acting as nicely.
try {
$webRequest = Invoke-WebRequest -URI "http://###.##.###.##:####/abcd.aspx?"
} catch [System.NullReferenceException]{
Write-Host "There is no data"
}
The full error displays in console, and the Write-Host never actually appears.

Answer 1

try {
$webRequest = Invoke-WebRequest -URI "http://host/link" -erroraction stop
}
catch [System.NullReferenceException]{
Write-Host "There is no data"
}
Powershell distinguishes between terminating and non terminating errors, for catch to work, you need the error to be terminating. https://blogs.technet.microsoft.com/heyscriptingguy/2015/09/16/understanding-non-terminating-errors-in-powershell/
UPD: to get the type of exception, after you get the error just do:
$Error[0].Exception.GetType().FullName
and you use that to catch that specific error after
to continue on specific error with invoke-webrequest you can do something like this:
try { Invoke-WebRequest "url" }
catch { $req = $_.Exception.Response.StatusCode.Value__}
if ($req -neq 404) { do stuff }

Answer 2

That's probably because the exception may not be a Null Reference exception. I Initially thought it to be a Non-Terminating error, but invoke-webrequest throws a terminating error.
In this case, you may simply try (without catching a specific exception type)
--Edited Per OP Comments--
try
{
Invoke-WebRequest -URI "http://doc/abcd.aspx?" -ErrorAction Stop
}
catch
{
if($_.Exception.GetType().FullName -eq "YouranticipatedException")
{
Write-Host ("Exception occured in Invoke-WebRequest.")
# You can also get the response code thru "$_.Exception.Response.StatusCode.Value__" if there is response to your webrequest
}