TYPO3 Core

Not sure wether this behaviour is a bug or a missing feature or mis-configuration on my side.
I could not find a hint in the 8.x changelog documentation by searching for "composer", "depend", "package".

Scenario:
In TYPO3 8.3.1 in extension manager. A extension of type "typo3-cms-extension" exists and is required and installed via composer as composer package. That extension itself brings a requirement to further composer packages not of type "typo3-cms-extension". When pressing button "activate". A Exception is thrown in 8.3.1 in Extension Manager:

Exception output
"#1382276561: The package "XXX" depends on "YYY" which is not present in the system. (More information)"

A demo package composer file could be

{
"name": "demo/demo",
"description": "demo",
"type": "typo3-cms-extension",
"license": "proprietary",
"version": "1.2.3",
"require": {
"spipu/html2pdf": "~4.5.1"
},
"replace": {
"demo_demo": "self.version",
"typo3-ter/demo_demo": "self.version"
}
}

The exception is only thrown in extension manager.
This exception is not thrown when the extension is activated via EXT: typo3_console.