500 Internal Server Error

implode(): Invalid arguments passed (2)

#0 [internal function]: flight\Engine->handleError(2, 'implode(): Inva...', '/home/storage/6...', 120, Array)
#1 /home/storage/6/bf/ac/trkimoveis4/public_html/application/controller/Busca.php(120): implode(' - ', 'area-de-desenvo...')
#2 /home/storage/6/bf/ac/trkimoveis4/public_html/core/routes.php(274): fmvc\application\controller\Busca->resultado()
#3 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/core/Dispatcher.php(194): {closure}('locacao', 'galpao', 'area-de-desenvo...', NULL)
#4 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/core/Dispatcher.php(163): flight\core\Dispatcher::callFunction(Object(Closure), Array)
#5 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/Engine.php(368): flight\core\Dispatcher::execute(Object(Closure), Array)
#6 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/core/Dispatcher.php(219): flight\Engine->_start()
#7 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/core/Dispatcher.php(162): flight\core\Dispatcher::invokeMethod(Array, Array)
#8 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/core/Dispatcher.php(54): flight\core\Dispatcher::execute(Array, Array)
#9 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/Engine.php(98): flight\core\Dispatcher->run('start', Array)
#10 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/core/Dispatcher.php(219): flight\Engine->__call('start', Array)
#11 /home/storage/6/bf/ac/trkimoveis4/public_html/libraries/mikecao/flight/flight/Flight.php(97): flight\core\Dispatcher::invokeMethod(Array, Array)
#12 /home/storage/6/bf/ac/trkimoveis4/public_html/web/index.php(15): Flight::__callStatic('start', Array)
#13 /home/storage/6/bf/ac/trkimoveis4/public_html/index.php(9): require_once('/home/storage/6...')
#14 {main}