R data.table и STRING_ELT () ошибка: как исправить ошибку ‘символьный вектор’ против ‘char’?

После обновления с R 3.3 до R 3.4 у меня эта ошибка при использовании data.table пакет:

STRING_ELT() can only be applied to a 'character vector', not a 'char'

Кто-нибудь испытывал то же самое? Я думаю о понижении, чтобы «исправить» это.

Это информация о моей сессии:

> sessionInfo()
R version 3.4.0 (2017-04-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.2 LTS

Matrix products: default
BLAS: /usr/lib/libblas/libblas.so.3.6.0
LAPACK: /usr/lib/lapack/liblapack.so.3.6.0

locale:
[1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8
[4] LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8       LC_NAME=C                  LC_ADDRESS=C
[10] LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] bindrcpp_0.2      purrrlyr_0.0.2    readxl_1.0.0      stringr_1.2.0
[5] bit64_0.9-7       bit_1.1-12        dtplyr_0.0.2      data.table_1.10.4
[9] dplyr_0.7.1       purrr_0.2.2.2     readr_1.1.1       tidyr_0.6.3
[13] tibble_1.3.3      ggplot2_2.2.1     tidyverse_1.1.1

loaded via a namespace (and not attached):
[1] Rcpp_0.12.11     cellranger_1.1.0 compiler_3.4.0   plyr_1.8.4       bindr_0.1
[6] forcats_0.2.0    tools_3.4.0      jsonlite_1.5     lubridate_1.6.0  nlme_3.1-131
[11] gtable_0.2.0     lattice_0.20-35  pkgconfig_2.0.1  rlang_0.1.1      psych_1.7.5
[16] parallel_3.4.0   haven_1.0.0      xml2_1.1.1       httr_1.2.1       hms_0.3
[21] grid_3.4.0       glue_1.1.1       R6_2.2.2         foreign_0.8-69   modelr_0.1.0
[26] reshape2_1.4.2   magrittr_1.5     scales_0.4.1     rvest_0.3.2      assertthat_0.2.0
[31] mnormt_1.5-5     colorspace_1.3-2 stringi_1.1.5    lazyeval_0.2.0   munsell_0.4.3
[36] broom_0.4.2