Invoke-SqlCmd generates an exception in foreach loop? - sql-server

Question

I am running 2 different sql query one after the other to get the details from database using Invoke-Sqlcmd but getting an exception.
The WriteObject and WriteError methods cannot be called from outside the overrides of the BeginProcessing, ProcessRecord, and EndProcessing methods, and they can only be called from within the same thread. Validate that the cmdlet makes these calls correctly
Script:
$ok = "true"
$serverName = $env:COMPUTERNAME
$query1 = "SELECT * FROM sys.server_audits WHERE name = 'Login'"
$query2 = "SELECT * FROM sys.dm_server_audit_status WHERE name = 'Login' AND status_desc = 'STARTED'"
try
{
Write-Host "Getting running Sql Server Instance (online)"
$sqlInstances = (Get-Service -Name MSSQL$* | Where-Object { $_.status -eq "Running" }).Name
$sqlInstancesCount = $sqlInstances.Count
Write-Host $eventID "$sqlInstancesCount Sql Server Instance found"
if($sqlInstancesCount)
{
foreach($item in $sqlInstances)
{
$count = 0
$instanceName = $item -replace "MSSQL\$", ""
$sqlInstanceFullname = Join-Path -Path $serverName -ChildPath "\" | Join-Path -ChildPath $instanceName
Write-Host "Sql Server instance fullname - $sqlInstanceFullname"
while($count -lt 3)
{
Write-Host "Clear existing connection."
[System.Data.SqlClient.SqlConnection]::ClearAllPools()
Write-Host "Executing query - $query1"
$result1 = (Invoke-Sqlcmd -Query $query1 -ServerInstance $sqlInstanceFullname)
Start-Sleep -Seconds 30
Write-Host "Clear existing connection."
[System.Data.SqlClient.SqlConnection]::ClearAllPools()
Write-Host "Executing query - $query2"
$result2 = (Invoke-Sqlcmd -Query $query2 -ServerInstance $sqlInstanceFullname)
if($null -eq $result1)
{
$message = "$serverName - The SQL Server [Login] does not exist."
$ok = "false"
$count = $count + 1
}
elseif($null -eq $result2)
{
$message = "$serverName - The SQL Server [Login] is disabled."
$ok = "false"
$count = $count + 1
}
else
{
$message = "SQL Login is enabled and running."
$count = 3
$ok = "true"
}
}
}
}
else
{
$ok = "false"
throw "$serverName - SQL Server Instances might be offline or not exist!"
}
}
catch
{
throw $_
}
I have tried enclosing Invoke-Sqlcmd in brackets but still getting same exception so is there a way to remove existing thread or close the connection before executing another query.