Errors cause a kind of automatic no already, but warnings and notices
are only displayed at the end of the apt execution even through they
could effect the choice of saying yes/no to questions: E.g. if a
configuration (file) was ignored you wanted to have an effect or if an
external solver you used generated warnings suggesting that the solution
might be valid, but bogus non-the-less and similar things.

Note that this only moves those messages up to the question if the
answer is interactive – not if e.g. -y is used or no question is asked at
all so this has an effect only on interactive usage of apt(-get), not
script who might be parsing apt output.