Error switching themes

Switching themes generates this error:

Notice: Trying to get property of non-object in […]/wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 1100

Warning: Cannot modify header information – headers already sent by (output started at […]/wp-content/plugins/wp-super-cache/wp-cache-phase2.php:1100) in […]/wp-includes/pluggable.php on line 899

This is with default themes and no other plugins.

https://www.ads-software.com/plugins/wp-super-cache/