[FIX] hr_org_chart: Fix traceback on employee creation

While creating employee and selecting a company other than the current company,
saving record shows a traceback.

Currently xml template expects managers and children key returned from
/get_org_chart controller but /get_org_chart was returning blank dict, and which
is used as qweb context to render template.

Return {'managers': [], 'children': []} if _check_employee returns False

task-2000269

addons/hr_org_chart/controllers/hr_org_chart.py

@@ -53,7 +53,10 @@ class HrOrgChartController(http.Controller):
 
         employee = self._check_employee(employee_id, **kw)
         if not employee:  # to check
-            return {}
+            return {
+                'managers': [],
+                'children': [],
+            }
 
         # compute employee data for org chart
         ancestors, current = request.env['hr.employee.public'].sudo(), employee.sudo()