Issue with only 1 variable in the model

[adayim]

The explain_survival function will fail if there is only 1 variable in the model. As the code below will convert this data to a vector and the nrow(data) will return NULL. Hence the n will be NULL and line 220 will fail.

survex/R/explain.R

Line 175 in cb0852a

data <- possible_data[, -1]

This can be fixed by changing this line to

data <- possible_data[, -1, drop = FALSE]