What's happening is 0110 is being treated as in integer before it hits UserPage.js, therefore turning it into 110. If you manually add a % to the beginning of the username you'll see it works just fine: `/u/%0110', if the user still exist.
You can see the crude hack by checking here for the error: https://qgaba.com/u/0110
Then to see the % hack working go here: https://qgaba.com/u/%0110
Note: not sure why my links are not working in this post?