Wrong datatype for second argument in javascript_aggregator.module on line 50.

I am repeatedly being show this error:
warning: array_search() [function.array-search]: Wrong datatype for second argument in /home/user/public_html/domain/sites/all/modules/javascript_aggregator/javascript_aggregator.module on line 50.

Lines 49 and 50 read:
// If javascript_aggregator's preprocess function is there already, remove it.
if ($key = array_search('javascript_aggregator_preprocess_page', $theme_registry['page']['preprocess functions'])) {

Anyone can point me the way to fix this? Thanks,