Throws an error as elicitSlot when the invoking intent is not associated

[jperata]

Is your feature request related to a problem? Please describe.
Issue an elicitSlot response in a lambda with a slot name which isn't associated with the Intent which triggered the lambda then virtual Alexa accepts this and returns the Dialog elicitSlot response. However, this is an illegal operation as "real Alexa" throws an error as elicitSlot can only be issued with a slot name associated with the invoking intent.

Describe the solution you'd like
Throw an error similar to what Alexa does.

Describe alternatives you've considered
Keep logic as it is, it's a minor difference

Additional context
We should update the documentation