src/Routes/Controller.php
protected function resolveErrorAsHtml(RequestApplicationInterface $app, \Throwable $exception)
    {
        $actions = ['actionError'];
        if ($exception instanceof HttpException) {
            $actions[] = 'actionErrorHttp';
            $actions[] = 'actionErrorHttp' . $exception->statusCode;
        }
        $action = null;
        foreach ($actions as $possibleAction) {
            $action = $this->normalizeActionName($possibleAction, false);
            if (isset($action)) {
                break;
            }
        }
        if (!isset($action)) {
            return $this->resolveErrorAsPlainText($app, $exception);
        }
        return Reaction::$di->invoke([$this, $action], [$app, $exception]);
    }
protected function resolveErrorAsHtml(RequestApplicationInterface $app, \Throwable $exception)
    {
        $actions = ['actionError'];
        if ($exception instanceof HttpException) {
            $actions[] = 'actionErrorHttp';
            $actions[] = 'actionErrorHttp' . $exception->statusCode;
        }
        $action = null;
        foreach ($actions as $possibleAction) {
            $action = $this->normalizeActionName($possibleAction, false);
            if (isset($action)) {
                break;
            }
        }
        if (!isset($action)) {
            return $this->resolveErrorAsPlainText($app, $exception);
        }
        return Reaction::$di->invoke([$this, $action], [$app, $exception]);
    }
Resolve error as rendered html
@param RequestApplicationInterface $app
@param \Throwable                  $exception
@return ResponseBuilderInterface|ExtendedPromiseInterface
@throws NotFoundException