log_warnings() etc. not compatible with profvis

Thanks for this great package! As a python native dabbling with R, it's great to find something so ergonomic for logging. This isn't really an issue _per se_, but more of an FYI that if you try to run code with one of the `log_warnings()`, `log_errors()`, etc. functions active from inside of a `profvis` profiling session, you'll get the following error:

```
Error in globalCallingHandlers(warning = function(m) { :
should not be called with handlers on the stack
Calls: profvis ... ..stacktraceon.. -> -> globalCallingHandlers
Execution halted
```

It's probably not urgent to find a workaround, but a note in the documentation might be helpful for others who come across this as a surprise.