Given a quantile, check that it:
is a single number
is between 0 and 100, inclusive
Examples
# valid
casteval:::validate_quant(50)
casteval:::validate_quant(0)
casteval:::validate_quant(100)
casteval:::validate_quant(2.5)
# invalid
try(casteval:::validate_quant("50"))
#> Error in casteval:::validate_quant("50") : `quant` must be numeric
try(casteval:::validate_quant(-1))
#> Error in casteval:::validate_quant(-1) :
#> `quant` must be between 0 and 100
try(casteval:::validate_quant(c(25,75)))
#> Error in casteval:::validate_quant(c(25, 75)) :
#> `quant` must be exactly 1 number, received numeric vector of length 2