Error in building a R package: R CMD check

I’m building an R package named “abms” in R studio. I already prepared my main script file (the code and documenting it), but I have a problem. When I want to perform an R cmd check, it gives me the following error:

i Updating abms documentation
Error: object 'isFALSE' is not exported by 'namespace:xfun'
Ejecuci�n interrumpida

Exited with status 1.

The strange thing is, this error started happening when I updated my R studio. I went back to the version I had before, but the error persists. I already updated all my packages (including the xfun package) and tried to search for a solution without success…

Do you know what I could do? It seems to me that R is trying to internally use the “isFALSE” function by calling it from the “xfun” package, where there is no function in such a package. But if that is the case, I don’t know how to change the package for which the “isFALSE” function is being called.

For any help, thank you in advance.