[kgwgk]

  # cat /tmp/test.R
  x <- 1:10
  y <- 1:20
  plot(x, y)

  # R --quiet
  > source("/tmp/test.R")
  Error in xy.coords(x, y, xlabel, ylabel, log) :
    'x' and 'y' lengths differ
  > traceback()
  8: stop("'x' and 'y' lengths differ")
  7: xy.coords(x, y, xlabel, ylabel, log)
  6: plot.default(x, y)
  5: plot(x, y) at test.R#3
  4: eval(ei, envir)
  3: eval(ei, envir)
  2: withVisible(eval(ei, envir))
  1: source("/tmp/test.R")

If you mean the lines in the packages you used, I think you'll see the lines if you build them with keep.source=TRUE