Database information and drive space in one function

Good day all,

I'm trying to come up with a function that I can run across all mailbox servers in my environment; gathering information such as drives presented to it, drive capacity, drive free space, database size, mbx count, avg mbx size, database whitespace, etc.. I start running into errors when I wanted to add the drive report to this. Can anyone take a look and see where im faulting? When I run this I get  "you cannot call a method on a null-valued expression.'

Thank you for your help.

function DatabaseStatistics{
$ExchangeServers = get-exchangeserver
$Drivespace = Get-wmiobject win32_logicaldisk -computername $ExchangeServers
   foreach($Drive in $drivespace) {
         $DrFree = $drivespace.deviceid.freespace
         $DrSize = $drivespace.deviceid.volumename.size

  $Databases = Get-MailboxDatabase * -Status
    foreach($Database in $Databases) {
        $DBSize = $Database.DatabaseSize
        $MBCount = @(Get-MailboxStatistics -Database $Database.Name).Count
        
        $MBAvg = Get-MailboxStatistics -Database $Database.Name | 
          %{$_.TotalItemSize.value.ToMb()} | 
            Measure-Object -Average  

        New-Object PSObject -Property @{
            Server = $Database.Server.Name
            DatabaseName = $Database.Name
            LastFullBackup = $Database.LastFullBackup
            MailboxCount = $MBCount
            "DatabaseSize (GB)" = $DBSize.ToGB()"AverageMailboxSize (MB)" = $MBAvg.Average"WhiteSpace (MB)" = $Database.AvailableNewMailboxSpace.ToMb()"Drive and Capacity" = $drsize.toGB()"Drive Freespace" = $drfree.toGB()
        }
    }
    }
    }