single line .lintr without trailing linebreak

[gdkrmr]

a .lintr file with a single line without trailing \n gives the following error, when calling Rscript -e 'lintr::lint_package()':

Error in mapply(function(from, to) paste(lines[from:to], collapse = "\n"),  : 
  zero-length inputs cannot be mixed with those of non-zero length
Calls: <Anonymous> -> read_settings -> read.dcf -> mapply
Execution halted

[jimhester]

This seems to be a duplicate of #160