Incorrect error message in router.js
Merge pull request #3325 from rutinerad/patch-1

Incorrect error message in router.js
Improve message and logic around UnrecognizedURLError
Merge pull request #3326 from trek/improve-message-and-logic-for-unrecognzied-urls

Improve message and logic around UnrecognizedURLError
Only throw an initialValue error if it is null or undefined (i.e. not 0 or some other falsy value)
Merge pull request #3327 from matthooks/master

Allow reduceComputed to have an initial value of 0.
Add shortcut for whitelisting all modifier keys on {{action}}
Modifier key-independent action helper use cases can be less verbose and more future-proof.