message: be clear that StateAction.params need to work without data object
diff: @@ -19,7 +19,7 @@ interface StateAction<A extends StateObject = StateObject, T = any, P extends {}
  readonly id: UUID,
  readonly definition: StateAction.Definition<A, T, P>,
  /** create a fresh copy of the params which can be edited in place */
  - createDefaultParams(a: A, globalCtx: unknown): P
  + createDefaultParams(a: A | undefined, globalCtx: unknown): P
  }
  namespace StateAction {
  @@ -54,7 +54,7 @@ namespace StateAction {
  export interface Definition<A extends StateObject = StateObject, T = any, P extends {} = {}> extends DefinitionBase<A, T, P> {
  readonly from: StateObject.Ctor[],
  readonly display: { readonly name: string, readonly description?: string },
  - params?(a: A, globalCtx: unknown): { [K in keyof P]: PD.Any }
  + params?(a: A | undefined, globalCtx: unknown): { [K in keyof P]: PD.Any }
  }
  export function create<A extends StateObject, T, P extends {} = {}>(definition: Definition<A, T, P>): StateAction<A, T, P> {
  