On line 275 of esi.module it appears to send a null variable to be altered, rather than the $components var that was just prepared.
Converting that to $components resolves this issue.
Adding my patch (dropped on validation),.
... I can confirm the RTBC
Fixed and committed in f5d4066b313fa254b7f96b663ca4460eedd29d59 - thanks!
Automatically closed -- issue fixed for 2 weeks with no activity.
This issue has no child issues.
Drupal is a registered trademark of Dries Buytaert.