You are totally right, but I didn't changed the behaviour here!
before we had "return $this->configSource->addRepository(...)"
where $this->configSource->addRepository(...) returned void, so it was implicitly NULL.
now it is implicit null. and I guess null will be converted to an int on the Command return, so it will be ok.
Return codes on commands should be 0 if successfull and != 0 on errors? so for me it could be ok? Or am I wrong at this point?