Catch error for malformed URL

[th507]

Proposed fix for #19 .

This also adds minor compatibility changes for latest io.js.

[coveralls]

Coverage increased (+0.06%) to 97.12% when pulling 5a2212b on th507:master into c9304e6 on koajs:master.

[jonathanong]

it's supposed to fail. they are malformed URLs.

[th507]

@jonathanong Theoretically, yes. But when using trie-router in production environment, we would like to redirect all unmatched URLs to a nice error page.

IMHO, router (along with Koa) should allow developer to redirect error to a specific page.
The 'problem' with trie-router is that it proactively throws a "Malformed URL" error and returns a 404 page, which breaks the conventional way of handling error with Koa's middleware.

[jonathanong]

i'd rather throw a very specific error with an err.code that you could try/catch upstream. this allows devs to do whatever they wish with the error, including re-throwing as a 404

[tejasmanohar]

👍 for specific error available for try/catch upstream

[tejasmanohar]

This PR except with a specific err.code is available here -> #22 @jonathanong
and the test script changes are here -> #23