Radiobutton reset option interferes with factorize_secuTrial()

[PatrickRWright]

Describe the bug
If the reset option is enabled for radio buttons (i.e. "at the beginning"/"at the end") this seems to cause an error in factorize_secuTrial().

Presumably, this is because the cl table contains an entry for the reset option for which the code is NA. I assume the according rows can be removed from lookup before this line.

data[, paste0(name, ".factor")] <- factorize_secuTrial(data[, name], lookup)

To Reproduce
Export data from a secuTrial DB which has a radio button with the reset option enabled and run read_secuTrial_raw() followed by factorize_secuTrial().

Expected behavior
No error.