message: mol-state: use produce in "old params" update
diff: @@ -10,6 +10,7 @@ import { StateObject, StateObjectCell, StateObjectSelector, StateObjectRef } fro
  import { StateTransform } from '../transform';
  import { StateTransformer } from '../transformer';
  import { State } from '../state';
  +import { produce } from 'immer';
  export { StateBuilder }
  @@ -231,7 +232,7 @@ namespace StateBuilder {
  let params: any;
  if (provider) {
  const old = this.state.tree.transforms.get(this.ref)!;
  - params = provider(old.params as any);
  + params = produce(old.params, provider);
  } else {
  params = typeof paramsOrTransformer === 'function'
  ? paramsOrTransformer(this.state.tree.transforms.get(this.ref)!.params)
  