No transition exists to move from to {state}

Thanks for this module!

Problem:
After adding a new workflows field to a node type of which there already exist nodes, it becomes impossible to save those nodes.

Error message shown when saving a node after a workflows_field field has been added to its node type:

No transition exists to move from to {state}.

Reason:
it's impossible to define a transition from state '' (empty) to any other state.

Not sure if this is a problem with workflows_field or workflows itself.

Thanks.
J.