A way to store reusable error handling code

[lasseebert]

Right now it is possible to reuse error handling code by using the pretty clumsy and undocumented self inside the kase block:

kase result do
  on(:ok) { |result| do_something_with(result) }
  common_error_handle(self)
end

with a error handling method like this:

def common_error_handle(matcher)
  matcher.on(:not_found) { render_not_found }
  matcher.on(:not_authorized) { render_not_authorized }
end

This will act as though the on methods from the common error handler was called inside the kase block.

This should be more explicit and also easier to swap on set of error handling with another.

Something like this:

common_error_handler = Kase::Handler.new do
  on(:not_found) { render_not_found }
  on(:not_authorized) { render_not_authorized }
end

kase result do |matcher|
  on(:ok) { |result| do_something_with(result) }
  apply(common_error_handler)
end

A Handler should store the on calls and maybe expose them for modification.

[lasseebert]

After some thought, I think the above example is bad practice. We should not have a list of 27 common error handlers applied to each e.g. http endpoint.