odoo 14 Unhandled Promise done is not a function

I am facing a problem this.get_critical_paths(events).done is not a function

When I tried debugging the problem I can see the console.log(paths)

Then I got this

Unhandled Promise Rejection: ReferenceError: Can't find variable: paths

I am not sure what to do to fix the problem. This is the code that should return the paths var

@api.model

def calc_critical_paths(self, project_ids):

    res = {}

    projects = self.env['project.project'].browse(project_ids)

    for project in projects:

        res.update({

            project.id: self.calc_critical_path(project)

        })

    return res

I am trying to upgrade The project timeline critical path

Kindly give suggestions to improve the question instead to dismissing it

from odoo 14 Unhandled Promise done is not a function