Trouble installing on MacOS

Hi, hopefully someone can help. 
```
remotes::install_github('tiagodc/TreeLS') 
```
gives me: 
> Error: Failed to install 'TreeLS' from GitHub: Failed to `R CMD build` package, try `build = FALSE`.
and 
```
remotes::install_github('tiagodc/TreeLS', build = FALSE)
```
doesn't work either. 
Xcode is installed.

Regards, 

Patrick 

