Bug of gs_design_ahr for information fraction driven design with number of analyses >= 4

[LittleBeannie]

The following code give error message:

library(gsDesign2)

gs_design_ahr(
  enroll_rate = define_enroll_rate(
    duration = c(2, 2, 2, 18), rate = 1:4
  ),
  fail_rate = define_fail_rate(
    duration = c(3, 100), fail_rate = log(2) / c(9, 18), hr =
      c(0.9, 0.6), dropout_rate = 0.001
  ),
  alpha = 0.025,
  beta = 0.1,
  info_frac = c(0.4, 0.6, 0.9, 1),
  analysis_time = 60,
  ratio = 1,
  binding = FALSE,
  upper = gs_spending_bound,
  upar = list(sf = gsDesign::sfLDOF, total_spend = 0.025, param = NULL, timing = NULL),
  lower = gs_spending_bound,
  lpar = list(sf = gsDesign::sfLDOF, total_spend = 0.1, param = NULL, timing = NULL),
  h1_spending = TRUE,
  test_upper = TRUE,
  test_lower = TRUE,
  info_scale = "h0_h1_info",
  r = 18,
  tol = 1e-06
)

Error in if (!is.numeric(lower) || !is.numeric(upper) || lower >= upper) stop("lower < upper  is not fulfilled") : 
  missing value where TRUE/FALSE needed
Error in expected_time(enroll_rate = enroll_rate, fail_rate = fail_rate,  : 
  expected_time(): solution not found!