pMap docstring + error catching

[andreibratu]

• p-map dependency could not be adequately imported in some node configurations
• Removed the dependency and added a homebrewed implementation; the implementation is not 1:1 with the dependency (e.g. not all options available), but preserves the logic we're interested in

[jamesbaskerville]

seems reasonable to me -- tested and works?

[andreibratu]

@jamesbaskerville yep, tested with cookbook examples + jordan's demo app. For SDLC, we should replicate the integration tests from Python in TS.