implode warning filling error log

[matdave]

The implode statement here

getPage/core/components/getpage/include.getpage.php

Line 35 in ec41b57

$nav['pages'] = implode("\n", $nav['pages']);

is creating a warning in the error log.

[2019-02-19 10:27:39] (ERROR @ /www/core/components/getpage/include.getpage.php : 35) PHP warning: implode(): Invalid arguments passed

I'm not sure how to reproduce, but adding a validator to ensure $nav['pages'] is set stops the warning.