Fixed error handling

backup_aragorn.psm1

@@ -20,7 +20,7 @@ function backup_aragorn {
     # Setup to use 7zip
     if (! (Test-Path 'C:\Program Files\7-Zip\7z.exe')) {
         Write-Error "Unable to locate 7-zip program file"
-        exit 1
+        throw 'Unable to locate 7-zip executable'
     }
     Set-Alias sz 'C:\Program Files\7-Zip\7z.exe'
     
@@ -75,7 +75,7 @@ function backup_aragorn {
 }
 
 # Get the age of the backup to make sure we are using the right disk
-function check_disk($diskoverride) {
+function check_disk($diskoverride=$false) {
 
     $backupDisk = Get-WmiObject -Class Win32_LogicalDisk | Where-Object {$_.VolumeName -match "Backup"}
     $partialBackup = $false
@@ -85,7 +85,7 @@ function check_disk($diskoverride) {
     if ($last_updated.AddDays(20) -lt (Get-Date)) {
         if (!($diskoverride)) {
             Write-Host -ForegroundColor DarkRed "This disk was last used less than 3 weeks ago. Override with -diskoverride."
-            exit(1)
+            throw 'Unable to proceed'
         }
     }
 
@@ -93,7 +93,7 @@ function check_disk($diskoverride) {
     # How much free space is there?
     if ($backupDisk.FreeSpace / 1gb -lt 20) {
         Write-Host -ForegroundColor DarkRed "There is less than 20gb free on the disk."
-        exit(1)
+        throw 'Unable to proceed'
     }