Airmail crashes CiviCRM event registrations when Smarty3 is enabled

[bugfolder]

We're using Airmail extension with ElasticEmail.

CiviCRM 5.69 encouraged enabling of Smarty3 in civicrm.settings.php by adding this code:

define('CIVICRM_SMARTY3_AUTOLOAD_PATH',
  '/mysite/modules/civicrm/packages/smarty3/vendor/autoload.php');

However, after doing so, when a user attempts to register for an event, at the last confirmation step, the (Backdrop CMS) site crashes. The dblog gets several of the following notices:

Notice: Indirect modification of overloaded property CRM_Core_Smarty::$template_dir has no effect in _airmail_civix_civicrm_config() (line 100 of /mysite/civicrm_extensions/com.aghstrategies.airmail/airmail.civix.php).

And then there is a crash notice:

TypeError: Unsupported operand types: float + string in content_65a9a73e803344_16150742() (line 406 of /mysite/modules/contrib/civicrm/packages/smarty3/vendor/smarty/smarty/libs/sysplugins/smarty_resource_recompiled.php(52) : eval()'d code).

If, however, I disable the Airmail extension, the registration goes through with no problem (except no email goes out, of course).

And similarly, if I comment out the Smarty3 definition in civicrm.settings.php, there is no problem; the registration goes through.

Any idea what the problem would be? For now I can turn off Smarty3, but CiviCRM says future versions will require it.

[bugfolder]

This looks like what is referenced here: https://lab.civicrm.org/dev/core/-/issues/4146.

[bugfolder]

Hi, could the developers comment on their timeline for getting a Smarty3-compatible version of this extension?

[bugfolder]

Upgraded to Airmail 2.2.2; I still see the notice (this time on the CiviCRM status page):

Notice: Indirect modification of overloaded property CRM_Core_Smarty::$template_dir has no effect in _airmail_civix_civicrm_config() (line 100 of /mysite/civicrm_extensions/com.aghstrategies.airmail/airmail.civix.php).

[chrisgaraffa]

Hi @bugfolder, 2.2.3 was released yesterday and should address this.

[bugfolder]

Wonderful, I'll try it out.

[chrisgaraffa]

Sorry, there's an issue with that release and we've pulled it. I'll be updating again early next week!

[bugfolder]

OK