May have been useful in its time

This plugin hasn’t been maintained in some time. You are likely to generate this error in your debug log:

:  Function register_rest_route was called <strong>incorrectly</strong>. The REST API route definition for <code>wqc/v1/query</code> is missing the required <code>permission_callback</code> argument. For REST API routes that are intended to be public, use <code>__return_true</code> as the permission callback.

This error goes away after de-activating the plugin.