R Error: Expecting a single string value: [type=character; extent=5]

I am working with the R programming language. I am using the "CORELS" library in R, here is an example (CORELS is a statistical model that is similar to a decision tree):

library(corels)

logdir <- tempdir()
rules_file <- system.file("sample_data", "compas_train.out", package="corels")
labels_file <- system.file("sample_data", "compas_train.label", package="corels")
meta_file <- system.file("sample_data", "compas_train.minor", package="corels")

stopifnot(file.exists(rules_file),
          file.exists(labels_file),
          file.exists(meta_file),
          dir.exists(logdir))

corels(rules_file, labels_file, logdir, meta_file,
       verbosity_policy = "silent",
       regularization = 0.015,
       curiosity_policy = 2,   # by lower bound
       map_type = 1)       # permutation map
cat("See ", logdir, " for result file.")

The output can be viewed here:

OPTIMAL RULE LIST
if ({sex:Male,juvenile-crimes:>0}) then ({recidivate-within-two-years:Yes})
else if ({priors:>3}) then ({recidivate-within-two-years:Yes})
else ({recidivate-within-two-years:No})

My Question: I am still a bit confused as to how the syntax works for the above functions. For example, I am trying to use the above functions on the "iris" dataset:

data(iris)
head(iris)

  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1          5.1         3.5          1.4         0.2  setosa
2          4.9         3.0          1.4         0.2  setosa
3          4.7         3.2          1.3         0.2  setosa
4          4.6         3.1          1.5         0.2  setosa
5          5.0         3.6          1.4         0.2  setosa
6          5.4         3.9          1.7         0.4  setosa

Now, I tried to apply the "corles" function on the iris data set:

logdir <- tempdir()
rules_file <- iris
labels_file <- colnames(iris)

corels(rules_file, labels_file, logdir, 
       verbosity_policy = "silent",
       regularization = 0.015,
       curiosity_policy = 2,   # by lower bound
       map_type = 1)       # permutation map
cat("See ", logdir, " for result file.")

But this produces the following error:

Error in corels(rules_file, labels_file, logdir, verbosity_policy = "silent",  : 
  Expecting a single string value: [type=character; extent=5].

Can someone please show me how to fix this error?

Thanks

References: