Package check result: ERROR

Check: examples, Result: ERROR
  Running examples in ‘npDoseResponse-Ex.R’ failed
  The error most likely occurred in:
  
  > base::assign(".ptime", proc.time(), pos = "CheckExEnv")
  > ### Name: RegAdjust
  > ### Title: The regression adjustment estimator of the dose-response curve.
  > ### Aliases: RegAdjust
  > ### Keywords: (partial) local polynomial regression
  > 
  > ### ** Examples
  > 
  > ## No test: 
  >   library(parallel)
  >   set.seed(123)
  >   n <- 300
  > 
  >   S2 <- cbind(2 * runif(n) - 1, 2 * runif(n) - 1)
  >   Z2 <- 4 * S2[, 1] + S2[, 2]
  >   E2 <- 0.2 * runif(n) - 0.1
  >   T2 <- cos(pi * Z2^3) + Z2 / 4 + E2
  >   Y2 <- T2^2 + T2 + 10 * Z2 + rnorm(n, mean = 0, sd = 1)
  >   X2 <- cbind(T2, S2)
  > 
  >   t_qry2 = seq(min(T2) + 0.01, max(T2) - 0.01, length.out = 100)
  >   chk <- Sys.getenv("_R_CHECK_LIMIT_CORES_", "")
  >   if (nzchar(chk) && chk == "TRUE") {
  +     # use 2 cores in CRAN/Travis/AppVeyor
  +     num_workers <- 2L
  +   } else {
  +     # use all cores in devtools::test()
  +     num_workers <- parallel::detectCores()
  +   }
  >   Y_RA2 = RegAdjust(Y2, X2, t_eval = t_qry2, h = NULL, b = NULL, C_h = 7, C_b = 3,
  +                     print_bw = FALSE, degree = 2, deriv_ord = 0,
  +                     kernT = "epanechnikov", kernS = "epanechnikov",
  +                     parallel = TRUE, cores = num_workers)
  Error in .check_ncores(cores) : 32 simultaneous processes spawned
  Calls: RegAdjust -> mclapply -> .check_ncores
  Execution halted