Issue with load_all due to missing rprojroot

[mhesselbarth]

I currently ran into the issue that I couldn't use pkgload::load_all(). The issue was that I didn't have the rprojroot package installed, so it couldn't import rprojroot_find_package_root_file. However, due to the tryCatch call the error message was very confusing (namely that no DESCRIPTION file could be found).

I am not sure this is relevant for any other users, but I think the error message or the import of rprojroot could be improved.