fix a bug in column_spec, fix kable_as_image in windows
diff --git a/R/kable_as_image.R b/R/kable_as_image.R
index 48e47a4..4eabca3 100644
--- a/R/kable_as_image.R
+++ b/R/kable_as_image.R
@@ -59,6 +59,7 @@
   )
   temp_tex <- paste(temp_tex, collapse = "\n")
   temp_file <- paste0("table_", format(Sys.time(), "%Y-%m-%d_%H:%M:%S"))
+  file.create(paste0(temp_file, ".tex"))
   write_file(temp_tex, paste0(temp_file, ".tex"))
   system(paste0("xelatex -interaction=batchmode ", temp_file, ".tex"))
   temp_file_delete <- paste0(temp_file, c(".tex", ".aux", ".log"))