message: throw error instead of letting the query complete
diff: @@ -770,7 +770,7 @@ unique_ptr<LogicalOperator> JoinOrderOptimizer::Optimize(unique_ptr<LogicalOpera
  // this should only happen in case the sets are actually disjunct
  // in this case we need to generate cross product to connect the disjoint sets
  if (context.config.force_no_cross_product) {
  - return move(plan);
  + throw InvalidInputException("Query requires a cross-product, but 'force_no_cross_product' PRAGMA is enabled");
  }
  GenerateCrossProducts();
  //! solve the join order again
  