Return error in install completion handler

Fixes #206

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- Return error in install completion handler. [#206](https://github.com/passepartoutvpn/tunnelkit/issues/206)
+
 ## 3.3.2 (2021-06-26)
 
 ### Fixed

TunnelKit/Sources/Protocols/OpenVPN/OpenVPNProvider.swift

@@ -144,7 +144,7 @@ public class OpenVPNProvider: VPNProvider {
         }
         install(configuration: configuration) { (error) in
             guard error == nil else {
-                completionHandler?(nil)
+                completionHandler?(error)
                 return
             }
             let connectBlock = {