apachesolr_search_run() fails to handle the result of $query->abort_search

Recoverable fatal error: Argument 2 passed to apachesolr_search_process_response() must implement interface DrupalSolrQueryInterface, null given in apachesolr_search_process_response()

apachesolr_search_run() does the following:
list($final_query, $response) = apachesolr_do_query($query);

It then passes $final_query to apachesolr_search_process_response() (by default) which, as the error indicates, requires that its $query argument implements DrupalSolrQueryInterface.

The problem is that if a hook_apachesolr_query_alter() implementation aborted the query by setting $query->abort_search to TRUE, then apachesolr_do_query() returns array(NULL, array());

i.e. $final_query is NULL, rather than an object implementing DrupalSolrQueryInterface.