message: Add UNKNOWN case
diff: @@ -311,6 +311,7 @@ namespace vcpkg::Commands::Install
  install_package(paths, action.plan.binary_pgh.value_or_exit(VCPKG_LINE_INFO), &status_db);
  System::println(System::Color::success, "Installing package %s... done", action.spec);
  break;
  + case InstallPlanType::UNKNOWN:
  default:
  Checks::unreachable(VCPKG_LINE_INFO);
  }
  