`summary()` crashes on zero-row input

[dewittpe]

library(medicalcoder)
packageVersion("medicalcoder")
#> [1] '0.7.0.9000'

df0 <- data.frame(
  code = character(),
  patid = integer(),
  icdv  = integer(),
  dx    = integer()
)

charlson <- comorbidities(
  data      = df0,
  icd.codes = "code",
  id.vars   = "patid",
  icdv.var  = "icdv",
  dx.var    = "dx",
  method    = "charlson_quan2011",
  poa       = 1L,
  primarydx = 0L
)

summary(charlson)
#> Warning in max(object[["num_cmrb"]]): no non-missing arguments to max;
#> returning -Inf
#> Error in seq_len(max(object[["num_cmrb"]])): argument must be coercible to non-negative integer

^{Created on 2025-12-17 with reprex v2.1.1}