TYPO3 Core

How to reproduce:

- have a default and any other language created
- disable the second language for FE
- (not sure it is important, I have language mode strict for this page, no fallback)
- have error handling for 404 configured to show content from page
- have a 404 page (the one showing the content that should be displayed in 404 situations), in both default and translation
- preview any regular translated page (means, same BE Domain)
- provoke 404 situation by providing a non-valid URL for this language

Expectation: 404 content is visible for language you are in
Effect: 404 content in default / fallback language is displayed

When language gets enabled, expectation is met and content shows up translated just fine.