LQT has the following declaration:
'type' => array (
ApiBase :: PARAM_DFLT => 'newthreads',
ApiBase :: PARAM_TYPE => array( 'replies', 'newthreads' ),
ApiBase :: PARAM_ISMULTI => true,
With invalid input the value of 'type' is array(). This is unexpected. It should either complain that the value(s) are not one of the allowed values (preferred), or use the default value 'newthreads' (less preferred). PARAM_ISMULTI seems to bypass the regular checks.
This causes exceptions in other code in LiquidhThreads which excepts that the values are sane. I believe this is an issue that should be fixed in core.