Error with Channel module category_tree method

Not sure where the logic is going so I don’t have a fix here. On a page with the categories tag pair in the channel module I received the following error:

A PHP Error was encountered Severity: Notice Message: Undefined variable: channel_ids Filename: channel/mod.channel.php Line Number: 5832

I tracked it down to the following code:

if (count($channel_ids) && $strict_empty == 'yes')
{
 $sql .= "AND exp_channel_titles.channel_id IN ('".implode("','", $channel_id)."') ";
}

Two notes:

1) The variable “channel_ids” isn’t defined at all at this point. However, “channel_id” (no “s”) is defined. 2) I noticed in the 2.4 diff that the old code just checked if $channel_id was an empty string. So for now I reverted back to that so my page functions as expected.

I’m certainly interested in what the intended logic is here. My guess is that somewhere along the way $channel_id is supposed to be an array, but I wasn’t sure.