A warning implies something went wrong and (possibly) the user should do
something about it. However, warnings are not always used this way.
For example:
* When a fallback value for a `${..}` reference is used, this shouldn't
produce a warning (or notice) since using fallbacks is not something
bad.
* pulse telling you that it uses the default sink because no sink was
specified also does not warrant a warning (even notice may be too
high).
* Whenever polybar shuts down it produces a "Termination signal
received..." warning. Since there isn't a more proper way to shut down
polybar, it should not produce a warning. Same argument for a
`screenchange-reload`