avoid logging 'isPackageDirectory' errors
avoid logging 'isPackageDirectory' errors

The errors are typically not useful, and since this function is called
by the file indexer (checking to see if a file lives within a package
directory) it's quite expensive if errors are logged frequently.

JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio