Cannot convert object to DataFrame for build return value on c3Grid

I’m getting the following error on a simple c3Grid(Type.fetch())

"Cannot convert object to DataFrame for build return value: DataFrame.header[8]: Extraneous property "unit" on object type "DataFrameColumn".
value: {"type":"DataFrame","m_matrix":[[{"type":"DataFrameColumn","label":"id","dataType":"string","valueTy... [InvalidInputParam]"

How I coudd get around this?