Behavior of injector.partial(fn)() and injector.apply(fn) should be the same when an annotation is unavailable.

[groner]

Currently injector.apply(fn) doesn't tolerate missing services even if the target function has a default for the given argument or a value was provided by the caller. However, in this case the behavior of injector.partial(fn)() is often more desired. That is, if a value is provided by the caller or a function default, that can be used, and if no value is available the TypeError that results from calling a function with the wrong errors is informative enough.