System emails are not being sent through.

Description

I recently ran composer update on my Craft 3 install and went into my Craft Commerce 2 settings. I updated some config in there and saved it all. I then went into Settings->Email and tried testing my email address and I didn't receive anything at all. On further inspection I could see in the logs there was a deprecation error which was:

The `defineComponents` event on CraftVariable has been deprecated. Use the `init` event to register custom components instead.

Source of error

/Users/me/Sites/client/vendor/craftcms/cms/src/web/twig/Extension.php:1032

This made me think it was my email templates but on further inspection it seems to be the Mailer.php file or something.

Steps to reproduce

1. Updated Craft CMS 3 to latest stable release
2. Went into Settings->Email and hit 'Test Email'
3. Did not get any email back saying test successful

Additional info

• Craft version: 3.1.32.1
• PHP version: 7.3.4
• Database driver & version: mysql
• Plugins & versions:

Amazon S3 1.2.3
Asset Rev 6.0.2
Blitz 2.0.8
Contact Form 2.2.3
Craft Commerce 2.1.7
Craft Variants 1.0.1
Eager Beaver 1.0.4
Element API 2.5.4
Field Manager 2.0.5
Imgix 2.0.4
Kint 1.0.0
Redactor 2.3.2
Retour 3.1.16
Scout 1.2.1
SEOmatic 3.2.9
Stripe for Craft Commerce 2.0.1.1
Webperf 1.0.12
Wishlist 1.0.1
Wordsmith 3.0.5

Full stack trace of log warning below:

Start by reproducing the failure from Settings->Email using the listed Craft CMS, PHP, database, and plugin versions, then inspect the warning at vendor/craftcms/cms/src/web/twig/Extension.php:1032 and the mentioned Mailer.php area. Done means the test email is sent successfully and the reported deprecation warning no longer accompanies the failure.