"missing value where TRUE/FALSE needed" error vcd::mosaic

``` > library(vcd) Loading required package: MASS Loading required package: grid Loading required package: colorspace > library(MASS) > tbl = table(survey$W.Hnd,survey$Fold) > print(tbl) L on R Neither R on L Left 10 1 7 Right 88 17 113 > mosaic(tbl) Error in if (split_vertical[i]) { : missing value where TRUE/FALSE needed Calls: mosaic -> mosaic.default -> strucplot -> labeling Execution halted ``` Why am I getting this error, and how to fix the code? Easy paste code here: ``` library(vcd) library(MASS) tbl = table(survey$W.Hnd,survey$Fold) # survey is a library data set in MASS print(tbl) mosaic(tbl) # produces the above error ```