Fatal Error with PHP 7.1

Error in log:

Error: [] operator not supported for strings in {path_to_site}/modules/contrib/views_slideshow_rendered_entity_pager/views_slideshow_rendered_entity_pager.module on line 62

Very similar to this issue → .

Note: As of PHP 7.1.0, applying the empty index operator on a string throws a fatal error. Formerly, the string was silently converted to an array.

Put another way, you can look at the "backwards incompatibility" page of the release notes.

The empty index operator is not supported for strings anymore
Applying the empty index operator to a string (e.g. $str[] = $x) throws a fatal error instead of converting silently to array.

I'll try to upload a patch.