Are you sure that you get those messages after running just the first line of code, or you are sourcing the whole script? Because it seems like the warnings are related with you specifying font =1 in the forest() function. "1" is not a valid font name, maybe you are trying to specify font size using the wrong parameter?.
Please turn this into a minimal REPRoducible EXample (reprex)? A reprex makes it much easier for others to understand your issue and figure out how to help.
If you've never heard of a reprex before, you might want to start by reading this FAQ: