Vacation keeps loading

When I open the Vacation tab within the Easy Appointments plugin, the loading image displays indefinitely. I opened the browser console to find out if there are any errors and found this. Can you help me fix this issue?

JQMIGRATE: Migrate is installed, version 3.4.0
DevTools failed to load source map: Could not load content for https://salonshierr.nl/wp-content/plugins/easy-appointments/css/theme/main.css.map: HTTP-fout: statuscode 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for https://salonshierr.nl/wp-content/plugins/easy-appointments/js/bundle.js.map: HTTP-fout: statuscode 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
bundle.js?ver=3.11.9:2 GET https://salonshierr.nl/index.php?rest_route=/easy-appointments/v1/vacation?_wpnonce=67c3bc6826 404
(anoniem) @ bundle.js?ver=3.11.9:2
e.exports @ bundle.js?ver=3.11.9:2
e.exports @ bundle.js?ver=3.11.9:2
Promise.then (asynchroon)
l.request @ bundle.js?ver=3.11.9:2
r.forEach.l. @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
value @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
s @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
Kt @ bundle.js?ver=3.11.9:2
i @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
s @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
Kt @ bundle.js?ver=3.11.9:2
i @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
vc @ bundle.js?ver=3.11.9:2
wl @ bundle.js?ver=3.11.9:2
t.unstable_runWithPriority @ bundle.js?ver=3.11.9:2
Ba @ bundle.js?ver=3.11.9:2
xl @ bundle.js?ver=3.11.9:2
ol @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
t.unstable_runWithPriority @ bundle.js?ver=3.11.9:2
Ba @ bundle.js?ver=3.11.9:2
Ka @ bundle.js?ver=3.11.9:2
Qa @ bundle.js?ver=3.11.9:2
cl @ bundle.js?ver=3.11.9:2
Kl @ bundle.js?ver=3.11.9:2
render @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
n @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
n @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
(anoniem) @ bundle.js?ver=3.11.9:2
bundle.js?ver=3.11.9:2 Uncaught (in promise) Error: Error: Request failed with status code 404
at bundle.js?ver=3.11.9:2:866478
at s (bundle.js?ver=3.11.9:2:377716)
at Generator._invoke (bundle.js?ver=3.11.9:2:377469)
at Generator.throw (bundle.js?ver=3.11.9:2:378075)
at Kt (bundle.js?ver=3.11.9:2:580170)
at c (bundle.js?ver=3.11.9:2:580411)