We are using this datepicker for ATUM:
And it seems that if it detects some data attributes added to any field where is working that are not part of its valid options, it throws an error. Are you adding data attributes to any ATUM field or something like that?
Anyway, I've edited our customized Bootstrap datepciker plugin to only show that error when the debug option is enabled, so starting from the next ATUM version, this error shouldn't be shown anymore.
I hope this helps.