Slack Module error: array_merge(): Argument #2 is not an array at /Modules/Slack/Providers/SlackServiceProvider.php:221

[ePascalC]

I received the following error in the slack module:
[2020-01-21 21:56:21] production.ERROR: array_merge(): Argument #2 is not an array {"exception":"[object] (ErrorException(code: 0): array_merge(): Argument #2 is not an array at /home/user/public_html/example.com/Modules/Slack/Providers/SlackServiceProvider.php:221)
[stacktrace]
#0 [internal function]: Illuminate\Foundation\Bootstrap\HandleExceptions->handleError(2, 'array_merge(): ...', '/home/wpeurope/...', 221, Array)
#1 /home/wpeurope/public_html/support.wp-europe.org/Modules/Slack/Providers/SlackServiceProvider.php(221): array_merge(Array, NULL)

I fixed it now by adding a check on 'empty' (so also NULL) and that seems to work for me, but maybe a deeper analysis will be needed

   \Eventy::addAction('slack.post', function($conversation, $pretext, $fields = [], $color = '') {
       if (empty($fields))
            $fields = [];
            
        // Detect channel by mailbox.
        $channel = '';
        $mailbox_id = $conversation->mailbox_id;

[freescout-helpdesk]

Fixed in Slack Module v1.0.4