Avoid null object in Proxy Handler fn

[Canos]

I created an issue with the details.
#34

I don't know why this is happening to me but this simple check seems to work.

Tests are ok
Test Suites: 21 passed, 21 total
Tests: 223 passed, 223 total

Anything just let me know. Thanks for you iniatiative.

[cyberavisror]

+1

[Garefild]

Fix the commit message (rebase) "reducer.service: validate target[prop] is not null"
and I will manage it :)

and I will redesign this section in the next major version