Bugs in fixed_design when applying the AHR method to calculate the power

[LittleBeannie]

The following code gives errors.

fixed_design(method = "ahr", 
             enroll_rate = tibble::tibble(stratum = "All",
                                          duration = c(2, 2, 10),
                                          rate = c(30, 60, 90)), 
             fail_rate = tibble::tibble(stratum = "All",
                                        duration = c(3, 100),
                                        fail_rate = log(2) / c(9, 18),
                                        hr = c(.9, .6),
                                        dropout_rate = rep(.001, 2)), 
             ratio = 1, 
             event = 100,
             alpha = 0.025, # 1-sided Type I error
             power = NULL, # Power will be computed
             study_duration = NULL, # study duration will be computed
             event = 300
)