code: void expectNumberStrict(Node n, JSType type, String msg) {
      if (!type.isSubtypeOf(getNativeType(NUMBER_TYPE))) {
        registerMismatchAndReport(
            n, INVALID_OPERAND_TYPE, msg, type, getNativeType(NUMBER_TYPE), null, null);
      }
    }
docs: Expect the type to be a number or a subtype.