Streamline bug due to switch case w/out a break (CoffeeScript optimization)

buggy_.coffee

async = (_) ->
  setTimeout _, 1000

switch true
  when true
    alert 'about to start async'
    async _

# this never executes!
alert 'done w/ async'

buggy_.js

function async(_) {
  setTimeout(_, 1000);
}

switch (true) {
  case true:
    alert('about to start async');
    async(_);
}

// this never executes!
alert('done w/ async');

workaround_.js

function async(_) {
  setTimeout(_, 1000);
}

switch (true) {
  case true:
    alert('about to start async');
    async(_);

    // but when we add this explicit break:
    break;
}

// this does execute now:
alert('done w/ async');