This function checks whether the input is a proper name vector, i.e., a
vector of (non-trivial) character values.
is_name_vector(x, error = TRUE)If error = TRUE, either invisibly TRUE or an error is thrown.
If error = FALSE, invisibly TRUE or FALSE.
Any object.
In the case that x is not a proper name vector, either TRUE
(default) to throw an error or FALSE to return invisibly FALSE.