Convenience function for `nrow(pas) == 0`. This makes for more readable code in functions that need to test for this.
Examples
library(AirSensor2)
example_pas_pm25 %>% pas_isEmpty() %>% print()
#> [1] FALSE
example_pas_pm25 %>% pas_filter(latitude > 90) %>% pas_isEmpty() %>% print()
#> [1] TRUE