undefined method `to_a` for "abc":String

[imi-milaap]

There is already one similar open issue.
Consider a training set as"

[
        ["myself", 0, "#{my_name}"],
        ["friend", 1, "#{friend_name}"],
        ["family", 1, "#{member_name}"],
        ["other", 1, "#{other_name}"]
]

If all methods(my_name, friend_name etc) return same name, decision tree is breaking.