TYPO3 Core

When you insert a content element of the type "plugin" (internal: list) on a page and do not select any plugin from the list of available plugins, then the following exception is thrown:

No Content Object definition found at TypoScript object path "tt_content.list.20." 

Reason for this from a user perspective unclear error message relies in a template in ext:fluid_styled_content, where a check is missing.