Topic on Extension talk:Iframe

Using master on MW 1.35 with PHP 7.4 creates the following PHP warning:

Warning: array_key_exists() expects parameter 2 to be array, null given in /../w/extensions/Iframe/Iframe_body.php on line 138

I see the same issue with MediaWiki 1.37.2 and PHP 7.4.

I solved this by declaring `$wgIframe` as an array in `LocalSettings.php`:

<code>

$wgIframe = array();

wfLoadExtension( 'Iframe' ); # for embedding web sites, e.g. LBC map

$wgIframe['server']['google'] = [ 'scheme' => 'https', 'domain' => 'google.com' ];

</code>

By the way, I'm using MW 1.37.1, PHP 8.0.16.