2ad1630: BREAKING: remove attribute/cti transform from tokens-studio transform group, this is redundant. However, users might rely on it, therefore it is a breaking change.
a2b2a22: Account for undefined as a token value in transformers. This may happen if a token value is a reference, but the reference is broken. A fatal error in the transform makes it more difficult for the user to find out that they have broken references and to debug it, therefore we guard against it in our transformers.