Browser refresh during checkout causes errors

[bstocks]

If a user refreshes the browser during checkout, errors occur and checkout cannot be completed. This bug will happen no matter what stage of checkout you are on when you refresh the browser, but it doesn't throw console errors or prevent checkout progress until after step 2.

To reproduce:

meteor reset
add one of the default product options to cart (not logged in)
start checkout
create new user
enter shipping/billing info
refresh the browser
-> error

Browser console errors for reference:

Exception in template helper: undefined 
Exception in template helper: TypeError: Cannot read property 'length' of undefined
    at Object.Template.checkoutShipping.helpers.rates (http://localhost:3000/packages/reactioncommerce_core.js?28f85cb836419f26ee16c911d29a641b49918ec7:33563:37)
    at http://localhost:3000/packages/blaze.js?77c0809654ee3a10dcd5a4f961fb1437e7957d33:2693:16
    at http://localhost:3000/packages/blaze.js?77c0809654ee3a10dcd5a4f961fb1437e7957d33:1602:16
    at Object.Spacebars.call (http://localhost:3000/packages/spacebars.js?3c496d2950151d744a8574297b46d2763a123bdf:169:18)
    at Template.checkoutShipping.HTML.DIV.HTML.DIV.HTML.DIV.Blaze.Each.HTML.A.href (http://localhost:3000/packages/reactioncommerce_core.js?28f85cb836419f26ee16c911d29a641b49918ec7:33516:22)
    at null.<anonymous> (http://localhost:3000/packages/blaze.js?77c0809654ee3a10dcd5a4f961fb1437e7957d33:2503:27)
    at http://localhost:3000/packages/blaze.js?77c0809654ee3a10dcd5a4f961fb1437e7957d33:1795:16
    at Object.Blaze._withCurrentView (http://localhost:3000/packages/blaze.js?77c0809654ee3a10dcd5a4f961fb1437e7957d33:2029:12)
    at viewAutorun (http://localhost:3000/packages/blaze.js?77c0809654ee3a10dcd5a4f961fb1437e7957d33:1794:18)
    at Tracker.Computation._compute (http://localhost:3000/packages/tracker.js?192a05cc46b867dadbe8bf90dd961f6f8fd1574f:288:36)

[aaronjudd]

Will be fixed with #100