nextAction() {
    // Logger.module("AI").debug("[G:" + this.getGameSession().gameId + "] nextAction -> next action called for AI.");
    // reset cached card data
    this.flushCaches();

    // find next action
    if (this.getGameSession().isNew()) {
      return this.nextActionForNewGame();
    } if (this.getGameSession().isActive() && this.getGameSession().getCurrentPlayerId() === this.getMyPlayerId()) {
      return this.nextActionForActiveGame();
    }
  }
Returns next action ai will take given the current game session state, or null if no action.
@returns {Action|null}