Hi,
It is tough to help you because we can not reproduce your error - using a reproducible example would help (see FAQ: What's a reproducible example (reprex) and how do I do one? - meta - RStudio Community).
However, my guess would be that svm() is running complete.cases() and the object is not a vector. Have a look at your data - is it in the format you expect it to be (is it completely empty?)?
Matt