Date facets not displaying

I recently integrated facets into a site but while every other facet was working fine, the facet for "post date" didn't. On further investigation, I discovered that any facet that was related to date wasn't working.

Steps to reproduce

Install Facet, Create Facets and enable them in the block page.

Proposed resolution

There is an error in apachesolr/plugins/facetapi/query_type_date.inc while checking for date.
$raw_data['gap'] = (isset($response->facet_counts->facet_dates->{$this->facet['field']}->gap)) ?? FACETAPI_DATE_MINUTE;
It assigns "true" to "gap" thereby preventing the plugin from working properly.

Remaining tasks

User interface changes

API changes

Data model changes