Notice: Undefined index: ds_search_form_search_form_alter

I don't get how that even happens, how can I reproduce this ?

I just got this error and here's what I did:

1. Start with Drupal Commons 7.x-3.x-dev (snapshot from early July 2013)
2. Upload DS 7.x-2.4
3. Use admin>modules to enable 2 pieces of DS: (a) Display Suite, and (b) Display Suite Search
4. Save configuration
5. See error: "Notice: Undefined index: module in ds_search_form_search_form_alter() (line 589 of mydrupal/sites/all/modules/ds/modules/ds_search/ds_search.module)."

If I disable Display Suite Search then the error goes away

Important additions to #2:

My starting point was not just an ordinary Drupal Commons 7.x-3.x-dev. I had disabled every search module except for "Search 7.22". I just re-enabled a bunch of these search modules, including Custom Search, Commons Search Core, and Faceted Navigation for search. After re-enabling those, I can also re-enable Display Suite Search without any errors.

So maybe the problem is that Display Suite Search depends on some other search modules, and those dependencies are not properly described in the DS module info?

Comitted and pushed to 7.x-1.x and 7.x-2.x

Moving to 8.x-2.x

Committed and pushed on 8.x branch.