R RKEA - Not enough training instances with class labels (required: 1, provided: 0)!
I think your example sentences are too short as documents. The following modification (primarily to the first sample document) works without error:
data <- c("This is a longer and longer sentence.", "I am in an office.", "I'm working on a laptop.", "I have a glass of water.", "There is a wooden desk.", "I have an apple for lunch.")My guess is that with really short sentences, there aren't enough words that aren't keywords to use in building the model.