check_numeric: Check that a specific list element is a numeric value
In a-maldet/readall: Read FWF, DSV, EXCEL And SAS Files

Check that a specific list element is a numeric value

check_numeric(
  obj,
  attr,
  err_h,
  min_val = NULL,
  max_val = Inf,
  allow_na = FALSE,
  allow_null = FALSE,
  allow_inf = FALSE
)

`obj`	The list object, that should be checked
`attr`	A string holding the name of the list element, that should be checked.
`err_h`	An error handler.
`min_val`	An optional argument, defining a minimal allowed value.
`max_val`	An numeric argument, defining the maximal allowed value.
`allow_na`	Are `NA` values allowed?
`allow_null`	A logical, defining whether the argument is allowed to be `NULL`.
`allow_inf`	An optional logical, defining if the value `Inf` is allowed.