planning_view.xml
< gantt
js_class="planning_gantt"
form_view_id="%(planning_view_form_in_gantt)d"
date_start="start_datetime"
date_stop="end_datetime"
default_group_by="employee_id"
default_scale="week"
color="color"
plan="false"
scales="day,week,month,year"
precision="{'day': 'hour:full', 'week': 'day:full', 'month': 'day:full', 'year': 'day:full'}"
decoration-info="not is_published"
decoration-warning="publication_warning and is_published"
decoration-danger="overlap_slot_count > 0"
display_unavailability="1"
thumbnails="{'employee_id': 'image_128'}">










odoo.define('planning.PlanningGanttView', function (require) {
'use strict';

var GanttView = require('web_gantt.GanttView');
var PlanningGanttController = require('planning.PlanningGanttController');
var PlanningGanttModel = require('planning.PlanningGanttModel');

var view_registry = require('web.view_registry');

var PlanningGanttView = GanttView.extend({
config: _.extend({}, GanttView.prototype.config, {
Controller: PlanningGanttController,
Model: PlanningGanttModel,
}),
});

view_registry.add('planning_gantt', PlanningGanttView);

return PlanningGanttView;

});
I got this error.
Invalid view planning.slot.gantt definition in planning/views/planning_views.xml