warning: array_merge() [function.array-merge]: Argument #2 is not an array in autocategorise.module on line 154

If this is the same error reported in http://drupal.org/node/466388 it has been
fixed in HEAD on June 9, but your report indicates that you are using 1.4 (May 15).

I believe it's fixed in the developer repository. I am not familiar with it, but I sometimes
checked releases out of it via cvs commands. See also:
http://drupal.org/node/133304
http://drupal.org/node/320

Fixed in HEAD? Looks like HEAD was not commited since
may 2009, so it cannot be fixed there.

But there is no error in DEV version from 2009-Aug-29.

Szy.

It seems there has been an attempt to fix the problem in 6.x-1.x-dev but it doesn't fix it.

The problem is caused by an uninitialised variable.

Here is a patch against 6.x-1.x-dev that fixes the problem.

I think the problem stems from not testing if the $otherterms array is empty - if it is then Argument 2 ($otherterms) is not an array. By testing for this, I've overcome the problem. Here are the lines I added to the autocategorise.module in 6.x.1.4 from 154 to 158 which seem to have corrected the problem:

if ( empty( $otherterms )) {
} else {
$matches = array_merge($matches, $otherterms);
}

Never contributed code to someone else's Drupal module before so I'm not really sure how to get this included in a "dev" release.

The patch I already made in #8 fixes this problem.

Array merge doesn't care if you pass it an empty array, only if you pass it something that is not an array.

Seeing as it is good coding practice to initialize variables anyway, that's all that needs to be done.

This is fixed in the latest -dev release.