download and install instead of direct installation

Install-Wireguard.ps1

@@ -8,9 +8,14 @@ If ( IsAdmin )
     Else           { $URL = 'https://download.wireguard.com/windows-client/wireguard-x86-latest.msi' }
 
     ## Install package
-    Try { Start-Process "msiexec.exe" -ArgumentList "/i ${URL} /qn /norestart DO_NOT_LAUNCH=1" -Wait -ErrorAction Stop }
+    $Installer = Download-File -URL $URL
+    Try { Start-Process "msiexec.exe" -ArgumentList "/i ${Installer} /qn /norestart DO_NOT_LAUNCH=1" -Wait -ErrorAction Stop }
     Catch { LogErr $_.Exception.Message ; Exit }
 
+    ## Delete installer
+    Try { If ( Test-Path $Installer ) { Remove-Item $Installer -Force } }
+    Catch { LogErr $_.Exception.Message }
+
     ## Install manager service
     Try { Start-Process "${Env:ProgramFiles}\WireGuard\wireguard.exe" -ArgumentList '/installmanagerservice' -Wait -ErrorAction SilentlyContinue }
     Catch { LogErr $_.Exception.Message }