[Html-widget] Use of undef string in H::W::E::NullContainer::id

[Ash Berlin]

So i upgraded (finally) from 1.07 to 1.10 to use filedset elements (damn 
designers wanting styling on it) and I got a raft of errors. Well 
actually only two errors, but when they happen in a catalyst server 
running under the perl debugger, its quite long.

Anyway, the culprit was $name in sub H::W::E::NullContainer::id was 
unset, and yet it still went down that path (Line 96 and 102 gave the 
warnings.)

Ash