Modules unable to register Twig extensions if there are pending migrations

[mmikkel]

Description

Possibly related to #2831:

Updating from 3.0.3.1 to 3.0.5, Craft is unable to run database migrations due to the following exception:

LogicException
Unable to register extension "namespace\module\twigextensions\SomeTwigExtension" as extensions have already been initialized.

The exception is only thrown if there are pending database migrations. If the calls to Craft::$app->getView()->registerTwigExtension() are removed from the modules, the migrations/update completes successfully. After updating, the calls to registerTwigExtension() can be added back in without the exception being thrown on subsequent requests.

Steps to reproduce

1. Add a custom Twig extension to a module's constructor or init() method using Craft::$app->getView()->registerTwigExtension()
2. Make sure there are pending database migrations
3. Visit /admin to run the migrations
4. Confirm that a LogicException is thrown

Additional info

• Craft version: 3.0.5
• PHP version:
• Database driver & version:
• Plugins & versions:

[brandonkelly]

Yep that definitely sounds related to #2831, which has been fixed now.