cref reference format for label type `' undefined

You have to put the \label command after the \caption. Then, both \vref and \cref will work.

The reason for the error is that cleveref and varioref cannot determine the type of the label unless \caption is issued first. Putting the label after the caption will tell cleveref and varioref that the object's type is, in both of the examples you give, figure.