Add convenience method to present and log errors in lock view controller

Signed-off-by: Claudio Cambra <claudio.cambra@nextcloud.com>

shell_integration/MacOSX/NextcloudIntegration/FileProviderUIExt/Locking/LockViewController.swift

@@ -38,4 +38,9 @@ class LockViewController: NSViewController {
     @IBAction func closeAction(_ sender: Any) {
         actionViewController.extensionContext.completeRequest()
     }
+
+    private func presentError(_ error: String) {
+        Logger.lockViewController.error("Error: \(error, privacy: .public)")
+        descriptionLabel.stringValue = "Error: \(error)"
+    }
 }