exception root_numpy.RootNumpyUnconvertibleWarning

This warning is raised when root_numpy is unable to convert a branch into a column of a NumPy array because there is no converter for the type. If the user explicitly requests a branch that cannot be converted, an error is raised. If the user does not specify a list of branches in an attempt to convert all branches, then this warning is raised for each branch that cannot be converted and these branches are merely skipped.