Error(s) in re-building vignettes:
  ...
--- re-building 'a_intro_attempt.Rmd' using rmarkdown
--- finished re-building 'a_intro_attempt.Rmd'

--- re-building 'b_try_catch.Rmd' using rmarkdown
--- finished re-building 'b_try_catch.Rmd'

--- re-building 'c_adverbs.Rmd' using rmarkdown
 ----------- FAILURE REPORT -------------- 
 --- failure: the condition has length > 1 ---
 --- srcref --- 
: 
 --- package (from environment) --- 
attempt
 --- call from context --- 
silent_matrix(1:3, 2)
 --- call from argument --- 
if (class(res) == "try-error") {
    cat(paste(res), file = getOption("try.outFile", default = stderr()))
    return(invisible(structure(paste(res), class = "try-error", 
        condition = res)))
}
 --- R stacktrace ---
where 1: silent_matrix(1:3, 2)
where 2: eval(expr, envir, enclos)
where 3: eval(expr, envir, enclos)
where 4: withVisible(eval(expr, envir, enclos))
where 5: withCallingHandlers(withVisible(eval(expr, envir, enclos)), warning = wHandler, 
    error = eHandler, message = mHandler)
where 6: doTryCatch(return(expr), name, parentenv, handler)
where 7: tryCatchOne(expr, names, parentenv, handlers[[1L]])
where 8: tryCatchList(expr, classes, parentenv, handlers)
where 9: tryCatch(expr, error = function(e) {
    call <- conditionCall(e)
    if (!is.null(call)) {
        if (identical(call[[1L]], quote(doTryCatch))) 
            call <- sys.call(-4L)
        dcall <- deparse(call)[1L]
        prefix <- paste("Error in", dcall, ": ")
        LONG <- 75L
        sm <- strsplit(conditionMessage(e), "\n")[[1L]]
        w <- 14L + nchar(dcall, type = "w") + nchar(sm[1L], type = "w")
        if (is.na(w)) 
            w <- 14L + nchar(dcall, type = "b") + nchar(sm[1L], 
                type = "b")
        if (w > LONG) 
            prefix <- paste0(prefix, "\n  ")
    }
    else prefix <- "Error : "
    msg <- paste0(prefix, conditionMessage(e), "\n")
    .Internal(seterrmessage(msg[1L]))
    if (!silent && isTRUE(getOption("show.error.messages"))) {
        cat(msg, file = outFile)
        .Internal(printDeferredWarnings())
    }
    invisible(structure(msg, class = "try-error", condition = e))
})
where 10: try(f, silent = TRUE)
where 11: handle(ev <- withCallingHandlers(withVisible(eval(expr, envir, 
    enclos)), warning = wHandler, error = eHandler, message = mHandler))
where 12: timing_fn(handle(ev <- withCallingHandlers(withVisible(eval(expr, 
    envir, enclos)), warning = wHandler, error = eHandler, message = mHandler)))
where 13: evaluate_call(expr, parsed$src[[i]], envir = envir, enclos = enclos, 
    debug = debug, last = i == length(out), use_try = stop_on_error != 
        2L, keep_warning = keep_warning, keep_message = keep_message, 
    output_handler = output_handler, include_timing = include_timing)
where 14: evaluate::evaluate(...)
where 15: evaluate(code, envir = env, new_device = FALSE, keep_warning = !isFALSE(options$warning), 
    keep_message = !isFALSE(options$message), stop_on_error = if (options$error && 
        options$include) 0L else 2L, output_handler = knit_handlers(options$render, 
        options))
where 16: in_dir(input_dir(), evaluate(code, envir = env, new_device = FALSE, 
    keep_warning = !isFALSE(options$warning), keep_message = !isFALSE(options$message), 
    stop_on_error = if (options$error && options$include) 0L else 2L, 
    output_handler = knit_handlers(options$render, options)))
where 17: block_exec(params)
where 18: call_block(x)
where 19: process_group.block(group)
where 20: process_group(group)
where 21: withCallingHandlers(if (tangle) process_tangle(group) else process_group(group), 
    error = function(e) {
        setwd(wd)
        cat(res, sep = "\n", file = output %n% "")
        message("Quitting from lines ", paste(current_lines(i), 
            collapse = "-"), " (", knit_concord$get("infile"), 
            ") ")
    })
where 22: process_file(text, output)
where 23: knitr::knit(knit_input, knit_output, envir = envir, quiet = quiet, 
    encoding = encoding)
where 24: rmarkdown::render(file, encoding = encoding, quiet = quiet, envir = globalenv(), 
    ...)
where 25: vweave_rmarkdown(...)
where 26: engine$weave(file, quiet = quiet, encoding = enc)
where 27: doTryCatch(return(expr), name, parentenv, handler)
where 28: tryCatchOne(expr, names, parentenv, handlers[[1L]])
where 29: tryCatchList(expr, classes, parentenv, handlers)
where 30: tryCatch({
    engine$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)))
})
where 31: tools:::.buildOneVignette("c_adverbs.Rmd", "/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/attempt.Rcheck/vign_test/attempt", 
    TRUE, FALSE, "c_adverbs", "UTF-8", "/tmp/RtmpiJyZ9n/file19b5156f1e4.rds")

 --- value of length: 2 type: logical ---
[1] FALSE FALSE
 --- function from context --- 
function (...) 
{
    res <- try(.f(...), silent = TRUE)
    if (class(res) == "try-error") {
        cat(paste(res), file = getOption("try.outFile", default = stderr()))
        return(invisible(structure(paste(res), class = "try-error", 
            condition = res)))
    }
}
<bytecode: 0x25ab7f8>
<environment: 0x2cbef58>
 --- function search by body ---
 ----------- END OF FAILURE REPORT -------------- 
Fatal error: the condition has length > 1
--- re-building 'd_if.Rmd' using rmarkdown
--- finished re-building 'd_if.Rmd'

--- re-building 'e_conditions.Rmd' using rmarkdown
--- finished re-building 'e_conditions.Rmd'

--- re-building 'tests_and_coverage.Rmd' using rmarkdown
--- finished re-building 'tests_and_coverage.Rmd'

SUMMARY: processing the following file failed:
  'c_adverbs.Rmd'

Error: Vignette re-building failed.
Execution halted