Error in `as.vector(d_s[, lapply(.SD, class)])[1, ]`: incorrect number of dimensions

"create_img_db run using sequential and parallel loading returns same results"
"create_img_db run using sequential and parallel loading returns same results without all files"

Error in `data.table::fread(file, showProgress = FALSE, colClasses = "character", 
    nThread = nThread, fill = fill, sep = sep_load)`: input= must be a single character string containing a file name, a system command containing at least one space, a URL starting 'http[s]://', 'ftp[s]://' or 'file://', or, the input data itself containing at least one \n or \r

"find_exam run using sequential and parallel loading returns same results"

"load_all run using sequential and parallel loading returns same results"

"load_bib run using sequential and parallel loading returns same results"

"load_con run using sequential and parallel loading returns same results"

"load_dem run using sequential and parallel loading returns same results"

"load_dem_old run using sequential and parallel loading returns same results"

"load_dia run using sequential and parallel loading returns same results"

"load_enc run using sequential and parallel loading returns same results"

"load_lab run using sequential and parallel loading returns same results"

<subscriptOutOfBoundsError/error/condition>
Error in `which_rows[[x]]`: subscript out of bounds

"load_lno run using sequential and parallel loading returns same results"

Error in `if (is.na(file_info$size)) stop("File '", file, "' does not exist or is non-readable. getwd()=='", 
    getwd(), "'")`: argument is of length zero

## Description: Test load_mcm() function
d_fname <- list.files(folder_raw, full.names = TRUE)[grep("mcm.txt", list.files(folder_raw), ignore.case = TRUE)]
d_s <- suppressMessages(load_mcm(d_fname, nThread = 1))
d_p <- suppressMessages(load_mcm(d_fname, nThread = 2))
test_that("load_mcm run using sequential and parallel loading returns same results", {
if(OVERWRITE | !file.exists(paste0(folder_parse, "mcm.csv"))) {data.table::fwrite(d_s, paste0(folder_parse, "mcm.csv"), row.names = FALSE)}
l_s <- data.table::fread(paste0(folder_parse, "mcm.csv"), na.strings = "NA", strip.white = FALSE, colClasses = apply(d_s, 2, class))