sha1() expects parameter 1 to be string, array given

[arthurkirkosa]

[2018-07-30 14:07:08] local.ERROR: sha1() expects parameter 1 to be string, array given {"exception":"[object] (ErrorException(code: 0): sha1() expects parameter 1 to be string, array given at /var/www/example.com/vendor/botman/botman/src/Messages/Incoming/IncomingMessage.php:88)
[stacktrace]
#0 [internal function]: Illuminate\\Foundation\\Bootstrap\\HandleExceptions->handleError(2, 'sha1() expects ...', '/var/www/growth...', 88, Array)
#1 /var/www/example.com/vendor/botman/botman/src/Messages/Incoming/IncomingMessage.php(88): sha1(Array)
#2 /var/www/example.com/vendor/botman/botman/src/Traits/HandlesConversations.php(173): BotMan\\BotMan\\Messages\\Incoming\\IncomingMessage->getConversationIdentifier()
#3 [internal function]: BotMan\\BotMan\\BotMan->BotMan\\BotMan\\Traits\\{closure}(Object(BotMan\\BotMan\\Messages\\Incoming\\IncomingMessage), 0)
#4 /var/www/example.com/vendor/laravel/framework/src/Illuminate/Support/Arr.php(606): array_filter(Array, Object(Closure), 1)
#5 /var/www/example.com/vendor/laravel/framework/src/Illuminate/Support/Collection.php(471): Illuminate\\Support\\Arr::where(Array, Object(Closure))
#6 /var/www/example.com/vendor/botman/botman/src/Traits/HandlesConversations.php(174): Illuminate\\Support\\Collection->filter(Object(Closure))
#7 /var/www/example.com/vendor/botman/botman/src/BotMan.php(396): BotMan\\BotMan\\BotMan->loadActiveConversation()
#8 /var/www/example.com/app/Http/Controllers/BotmanController.php(19): BotMan\\BotMan\\BotMan->listen()
#9 [internal function]: App\\Http\\Controllers\\BotManController->handle()

// routes/botman.php

<?php

use App\Http\Controllers\BotManController;

$botman = app('botman');

$botman->on('team_join', BotManController::class.'@slackTeamJoin');

// BotMatContrller

<?php

namespace App\Http\Controllers;

use BotMan\BotMan\BotMan;
use App\Conversations\SlackTeamJoin;

class BotManController extends Controller
{
    /**
     * Place your BotMan logic here.
     */
    public function handle()
    {
        $botman = app('botman');

        logger()->info(request()->all());

        $botman->listen();
    }

    /**
     * @return \Illuminate\Contracts\View\Factory|\Illuminate\View\View
     */
    public function tinker()
    {
        return view('pages.tinker');
    }

    /**
     * Loaded through routes/botman.php
     *
     * @param  BotMan $bot
     */
    public function slackTeamJoin(BotMan $bot)
    {
        $text = file_get_contents(base_path('core/instructions.md'));

        $bot->replay($text);
    }
}

// logger->info

[2018-07-30 14:07:07] local.INFO: array (
  'token' => 'YdQetlQAzAJJyqNN3RyaKl93',
  'team_id' => 'TBSG4AS8J',
  'api_app_id' => 'ABTRKKFQW',
  'event' =>
  array (
    'type' => 'team_join',
    'user' =>
    array (
      'id' => 'UBZDVG805',
      'team_id' => 'TBSG4AS8J',
      'name' => 'name862',
      'deleted' => false,
      'color' => 'e7392d',
      'real_name' => 'Gigi Lanseta',
      'tz' => 'Europe/Athens',
      'tz_label' => 'Eastern European Summer Time',
      'tz_offset' => 10800,
      'profile' =>
      array (
        'title' => NULL,
        'phone' => NULL,
        'skype' => NULL,
        'real_name' => 'Gigi Lanseta',
        'real_name_normalized' => 'Gigi Lanseta',
        'display_name' => 'gigi',
        'display_name_normalized' => 'gigi',
        'fields' => NULL,
        'status_text' => NULL,
        'status_emoji' => NULL,
        'status_expiration' => 0,
        'avatar_hash' => 'g58edf7ee5c4',
        'image_24' => 'https://secure.gravatar.com/avatar/58edf7ee5c45c7fa9d33d0ceb50ce45d.jpg?s=24&d=https%3A%2F%2Fa.slack-edge.com%2F0180%2Fimg%2Favatars%2Fava_0017-24.png',
        'image_32' => 'https://secure.gravatar.com/avatar/58edf7ee5c45c7fa9d33d0ceb50ce45d.jpg?s=32&d=https%3A%2F%2Fa.slack-edge.com%2F66f9%2Fimg%2Favatars%2Fava_0017-32.png',
        'image_48' => 'https://secure.gravatar.com/avatar/58edf7ee5c45c7fa9d33d0ceb50ce45d.jpg?s=48&d=https%3A%2F%2Fa.slack-edge.com%2F66f9%2Fimg%2Favatars%2Fava_0017-48.png',
        'image_72' => 'https://secure.gravatar.com/avatar/58edf7ee5c45c7fa9d33d0ceb50ce45d.jpg?s=72&d=https%3A%2F%2Fa.slack-edge.com%2F66f9%2Fimg%2Favatars%2Fava_0017-72.png',
        'image_192' => 'https://secure.gravatar.com/avatar/58edf7ee5c45c7fa9d33d0ceb50ce45d.jpg?s=192&d=https%3A%2F%2Fa.slack-edge.com%2F7fa9%2Fimg%2Favatars%2Fava_0017-192.png',
        'image_512' => 'https://secure.gravatar.com/avatar/58edf7ee5c45c7fa9d33d0ceb50ce45d.jpg?s=512&d=https%3A%2F%2Fa.slack-edge.com%2F7fa9%2Fimg%2Favatars%2Fava_0017-512.png',
        'status_text_canonical' => NULL,
        'team' => 'TBSG4AS8J',
      ),
      'is_admin' => false,
      'is_owner' => false,
      'is_primary_owner' => false,
      'is_restricted' => false,
      'is_ultra_restricted' => false,
      'is_bot' => false,
      'is_app_user' => false,
      'updated' => 1532959260,
      'presence' => 'away',
    ),
    'cache_ts' => 1532959260,
    'event_ts' => '1532959260.000107',
  ),
  'type' => 'event_callback',
  'event_id' => 'EvC0K57FN2',
  'event_time' => 1532959260,
  'authed_users' =>
  array (
    0 => 'UBRSHE0M6',
    1 => 'UBSG4ASR0',
  ),
)

What I'm trying to achieve is when a new member joins the team, have the bot send him the contents of that md file (multi line text)

What am I doing wrong?

The bot is listening to the demo sample code (Hello, Hi)