Error(s) in re-building vignettes:
  ...
--- re-building ‘get_nltt_values.Rmd’ using rmarkdown
Warning in .make_numeric_version(x, strict, .standard_regexps()$valid_numeric_version) :
  invalid non-character version specification 'x' (type: double)
Calls:
 1: tools:::.buildOneVignette("get_nltt_values.Rmd", "/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/nLTT.Rcheck/vign_test/nLTT", TRUE, FALSE, "get_nltt_values", "UTF-8", "/home/hornik/tmp/scratch/Rtmp7r14HO/file29b9e59af1379.rds")
 2: tryCatch({
        engine$weave(file, quiet = quiet, encoding = enc)
        setwd(startdir)
        output <- find_vignette_product(name, by = "weave", engine = engine)
        if (!have.makefile && vignette_is_tex(output)) {
            texi2pdf(file = output, clean = FALSE, quiet = quiet)
            output <- find_vignette_product(name, by = "texi2pdf", engine = engine)
        }
    }, error = function(e) {
        OK <<- FALSE
        message(gettextf("Error: processing vignette '%s' failed with diagnostics:\n%s", file, conditionMessage(e)))
    })
 3: tryCatchList(expr, classes, parentenv, handlers)
 4: tryCatchOne(expr, names, parentenv, handlers[[1L]])
 5: doTryCatch(return(ex [... truncated]
--- finished re-building ‘get_nltt_values.Rmd’

--- re-building ‘nltt_diff.Rmd’ using rmarkdown
Warning in .make_numeric_version(x, strict, .standard_regexps()$valid_numeric_version) :
  invalid non-character version specification 'x' (type: double)
Calls:
 1: tools:::.buildOneVignette("nltt_diff.Rmd", "/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/nLTT.Rcheck/vign_test/nLTT", TRUE, FALSE, "nltt_diff", "UTF-8", "/home/hornik/tmp/scratch/Rtmp7r14HO/file29b9e560b1b95e.rds")
 2: tryCatch({
        engine$weave(file, quiet = quiet, encoding = enc)
        setwd(startdir)
        output <- find_vignette_product(name, by = "weave", engine = engine)
        if (!have.makefile && vignette_is_tex(output)) {
            texi2pdf(file = output, clean = FALSE, quiet = quiet)
            output <- find_vignette_product(name, by = "texi2pdf", engine = engine)
        }
    }, error = function(e) {
        OK <<- FALSE
        message(gettextf("Error: processing vignette '%s' failed with diagnostics:\n%s", file, conditionMessage(e)))
    })
 3: tryCatchList(expr, classes, parentenv, handlers)
 4: tryCatchOne(expr, names, parentenv, handlers[[1L]])
 5: doTryCatch(return(expr), name,  [... truncated]
--- finished re-building ‘nltt_diff.Rmd’

--- re-building ‘nltts_plot.Rmd’ using rmarkdown
Warning in .make_numeric_version(x, strict, .standard_regexps()$valid_numeric_version) :
  invalid non-character version specification 'x' (type: double)
Calls:
 1: tools:::.buildOneVignette("nltts_plot.Rmd", "/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/nLTT.Rcheck/vign_test/nLTT", TRUE, FALSE, "nltts_plot", "UTF-8", "/home/hornik/tmp/scratch/Rtmp7r14HO/file29b9e5666415d5.rds")
 2: tryCatch({
        engine$weave(file, quiet = quiet, encoding = enc)
        setwd(startdir)
        output <- find_vignette_product(name, by = "weave", engine = engine)
        if (!have.makefile && vignette_is_tex(output)) {
            texi2pdf(file = output, clean = FALSE, quiet = quiet)
            output <- find_vignette_product(name, by = "texi2pdf", engine = engine)
        }
    }, error = function(e) {
        OK <<- FALSE
        message(gettextf("Error: processing vignette '%s' failed with diagnostics:\n%s", file, conditionMessage(e)))
    })
 3: tryCatchList(expr, classes, parentenv, handlers)
 4: tryCatchOne(expr, names, parentenv, handlers[[1L]])
 5: doTryCatch(return(expr), name [... truncated]
--- finished re-building ‘nltts_plot.Rmd’

--- re-building ‘stretch_nltt_matrix.Rmd’ using rmarkdown
Warning in .make_numeric_version(x, strict, .standard_regexps()$valid_numeric_version) :
  invalid non-character version specification 'x' (type: double)
Calls:
 1: tools:::.buildOneVignette("stretch_nltt_matrix.Rmd", "/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/nLTT.Rcheck/vign_test/nLTT", TRUE, FALSE, "stretch_nltt_matrix", "UTF-8", "/home/hornik/tmp/scratch/Rtmp7r14HO/file29b9e54d4de70c.rds")
 2: tryCatch({
        engine$weave(file, quiet = quiet, encoding = enc)
        setwd(startdir)
        output <- find_vignette_product(name, by = "weave", engine = engine)
        if (!have.makefile && vignette_is_tex(output)) {
            texi2pdf(file = output, clean = FALSE, quiet = quiet)
            output <- find_vignette_product(name, by = "texi2pdf", engine = engine)
        }
    }, error = function(e) {
        OK <<- FALSE
        message(gettextf("Error: processing vignette '%s' failed with diagnostics:\n%s", file, conditionMessage(e)))
    })
 3: tryCatchList(expr, classes, parentenv, handlers)
 4: tryCatchOne(expr, names, parentenv, handlers[[1L]])
 5: doTryCatch( [... truncated]
--- finished re-building ‘stretch_nltt_matrix.Rmd’

--- re-building ‘trees_with_root_edge.Rmd’ using rmarkdown
Error: processing vignette ‘trees_with_root_edge.Rmd’ failed with diagnostics:
(converted from warning) invalid non-character version specification 'x' (type: double)
Calls:
 1: tools:::.buildOneVignette("trees_with_root_edge.Rmd", "/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/nLTT.Rcheck/vign_test/nLTT", TRUE, FALSE, "trees_with_root_edge", "UTF-8", "/home/hornik/tmp/scratch/Rtmp7r14HO/file29b9e5555cde3d.rds")
 2: tryCatch({
        engine$weave(file, quiet = quiet, encoding = enc)
        setwd(startdir)
        output <- find_vignette_product(name, by = "weave", engine = engine)
        if (!have.makefile && vignette_is_tex(output)) {
            texi2pdf(file = output, clean = FALSE, quiet = quiet)
            output <- find_vignette_product(name, by = "texi2pdf", engine = engine)
        }
    }, error = function(e) {
        OK <<- FALSE
        message(gettextf("Error: processing vignette '%s' failed with diagnostics:\n%s", file, conditionMessage(e)))
    })
 3: tryCatchList(expr, classes, parentenv, handlers)
 4: tryCatchOne(expr, names, parentenv, handlers[[1L]])
 5: doTryCatc [... truncated]
--- failed re-building ‘trees_with_root_edge.Rmd’

--- re-building ‘walkthrough.Rmd’ using rmarkdown
Warning in .make_numeric_version(x, strict, .standard_regexps()$valid_numeric_version) :
  invalid non-character version specification 'x' (type: double)
Calls:
 1: tools:::.buildOneVignette("walkthrough.Rmd", "/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/nLTT.Rcheck/vign_test/nLTT", TRUE, FALSE, "walkthrough", "UTF-8", "/home/hornik/tmp/scratch/Rtmp7r14HO/file29b9e5288e4866.rds")
 2: tryCatch({
        engine$weave(file, quiet = quiet, encoding = enc)
        setwd(startdir)
        output <- find_vignette_product(name, by = "weave", engine = engine)
        if (!have.makefile && vignette_is_tex(output)) {
            texi2pdf(file = output, clean = FALSE, quiet = quiet)
            output <- find_vignette_product(name, by = "texi2pdf", engine = engine)
        }
    }, error = function(e) {
        OK <<- FALSE
        message(gettextf("Error: processing vignette '%s' failed with diagnostics:\n%s", file, conditionMessage(e)))
    })
 3: tryCatchList(expr, classes, parentenv, handlers)
 4: tryCatchOne(expr, names, parentenv, handlers[[1L]])
 5: doTryCatch(return(expr), na [... truncated]
--- finished re-building ‘walkthrough.Rmd’

SUMMARY: processing the following file failed:
  ‘trees_with_root_edge.Rmd’

Error: Vignette re-building failed.
Execution halted