Do not return a value if the index does not exist

[vanderlee]

If, for some reason, a non-existent value is set for the input, it will set undefined as the value for the input.
This change empties the value instead.
I don't know if this causes side-effects for other use cases, but it seems to work for me.

[ryantheleach]

I've seen the behaviour you described also, as well as when expecting an object, seeing a string instead.

e.g. I blank the input, press escape, and the sent value is the previous display value, rather then what I would expect: a empty / null value.

Even if it were expected behaviour to rollback, I would have expected to see the previous object, not the display string.