Adding an item in Hack023 client causes sync failure due to an invalid Url

[rayworks]

Hi there, I just found a issue about project Hack023.
There are the steps to reproduce the issue:

1. start the server and the run hack023 app
2. login with the valid account
3. add a new item named "go to school"

It seems the item added locally which turns red and can't be synced with the server when clicking button 'refresh'. Meanwhile I saw an IllegalArgumentException in stacktrace.

[Macarse]

@rayworks I am closing this since you fix it by your PR. Thanks!

[rayworks]

@Macarse Thank you !