array_merge arg not array and undefined index

Issue Summary

I'm receiving the following errors when saving the settings on admin/config/recommender/history_rec:
Warning: array_merge() [function.array-merge]: Argument #1 is not an array in recommender_app_update() (line 64 of sites/all/modules/contrib/recommender/recommender.module).
Warning: array_merge() [function.array-merge]: Argument #2 is not an array in recommender_app_update() (line 64 of sites/all/modules/contrib/recommender/recommender.module).
Notice: Undefined index: id in recommender_app_update() (line 67 of sites/all/modules/contrib/recommender/recommender.module).

I'm not sure if this is a problem with History Recommender's integration with the recommender API or if it's a problem with the recommender API itself, so feel free to move this to the recommender queue if necessary. I'm using recommender version 7.x-3.0-alpha11