R: compute the bootstrap estimate using rms:bootcov on caret model and glm model

How do I compute the bootstrap estimate for my regression coefficients using the function bootcov from the package rms? I tried the below with sample dataset but got an error:

library(mlbench)
data(PimaIndiansDiabetes)

library(caret)
trControl <- trainControl(method = "repeatedcv",
                          repeats = 3,
                          classProbs = TRUE,
                          number = 10, 
                          savePredictions = TRUE,
                          summaryFunction = twoClassSummary)

caret_model <- train(diabetes~., 
                     data=PimaIndiansDiabetes, 
                     method="glm", 
                     trControl=trControl)

library(rms)
set.seed(1234)
reduced_model_bootcov <- bootcov(caret_model$finalModel, B=100)

The error is:

Error in bootcov(caret_model$finalModel, B = 100) : you did not specify x=TRUE and y=TRUE in the fit

If I use the function glm to build the model, this is what I would do:

model <- glm(diabetes~., 
             data=PimaIndiansDiabetes, 
             family=binomial,
             x=TRUE, y=TRUE)
model_bootcov <- bootcov(model, B=100)

But again, I got a different error:

Error in bootcov(model, B = 100) : fitter not valid