How do I get the ELSE part of IF statement to output custom message when condition is not met in R?

I want to use an IF statement to output a gender/sex count if the table contains either gender or sex. I am using R markdown and want it to output a message such as "No gender/sex variable in this dataset" and move to the next block if there is no gender/sex variable in the dataset. If I run my code on a table that contain gender or sex it runs without any problem, but if the table does not contain gender or sex it will throw an error "Missing value where TRUE/FALSE needed", I want my own custom message instead of an error. below is my code:

sex_or_gender <- location %>%
  select_if(names(.) %in% "sex" | names(.) %in% "gender")

if(names(location) %in% "sex" || names(location) %in% "gender") {
    sex_or_gender %>%
        group_by(sex_or_gender[1] %>%
        summarise(sex_count = n())
} else{
     print("No gender/sex variable in this dataset")
}

Result should be either;
|sex| sex_count|
| M |   256    |
| F |   301    |
| NA|   25     |

or

|gender| sex_count|
|   M  |   256    |
|   F  |   301    |
|   NA |   25     |

or

No gender/sex variable in this dataset

NOTE: The returned data frame contains only one variable, either sex or date depending on which is used