Dynamic Content region must use a template with ID attribute

Question

I am getting following warnings/errors on browser's console. Need help to to trace and resolve these.

Service workers are not supported on HTTP pages.
Dynamic Content region must use a template with ID attribute
Uncaught Error: Region element not found R8673356286039918

desktop_all.min.js?v=23.1.0:5 Service workers are not supported on HTTP pages.
e.warn @ desktop_all.min.js?v=23.1.0:5
a.init @ desktop_all.min.js?v=23.1.0:56
(anonymous) @ brentity?p2_form_mode=A&session=23824403876947&cs=1hYXr2ArG3_e2gkrL3_LRx3UHQqIHPp6H0k1pUHyMPqYW0l-n6M2ZmPbAKGBSMgr7qYA-t1nqMXNobXExoxO09Q:2507
desktop_all.min.js?v=23.1.0:5 Dynamic Content region must use a template with ID attribute
e.error @ desktop_all.min.js?v=23.1.0:5
s @ desktop_all.min.js?v=23.1.0:53
(anonymous) @ desktop_all.min.js?v=23.1.0:53
e @ desktop_all.min.js?v=23.1.0:2
t @ desktop_all.min.js?v=23.1.0:2
setTimeout (async)
(anonymous) @ desktop_all.min.js?v=23.1.0:2
c @ desktop_all.min.js?v=23.1.0:2
fireWith @ desktop_all.min.js?v=23.1.0:2
fire @ desktop_all.min.js?v=23.1.0:2
c @ desktop_all.min.js?v=23.1.0:2
fireWith @ desktop_all.min.js?v=23.1.0:2
ready @ desktop_all.min.js?v=23.1.0:2
$ @ desktop_all.min.js?v=23.1.0:2
desktop_all.min.js?v=23.1.0:5 console.trace
e.error @ desktop_all.min.js?v=23.1.0:5
s @ desktop_all.min.js?v=23.1.0:53
(anonymous) @ desktop_all.min.js?v=23.1.0:53
e @ desktop_all.min.js?v=23.1.0:2
t @ desktop_all.min.js?v=23.1.0:2
setTimeout (async)
(anonymous) @ desktop_all.min.js?v=23.1.0:2
c @ desktop_all.min.js?v=23.1.0:2
fireWith @ desktop_all.min.js?v=23.1.0:2
fire @ desktop_all.min.js?v=23.1.0:2
c @ desktop_all.min.js?v=23.1.0:2
fireWith @ desktop_all.min.js?v=23.1.0:2
ready @ desktop_all.min.js?v=23.1.0:2
$ @ desktop_all.min.js?v=23.1.0:2
desktop_all.min.js?v=23.1.0:14 Uncaught Error: Region element not found R8673356286039918
    at l.create (desktop_all.min.js?v=23.1.0:14:1801)
    at new s (desktop_all.min.js?v=23.1.0:53:591)
    at HTMLDocument.<anonymous> (desktop_all.min.js?v=23.1.0:53:666)
    at e (desktop_all.min.js?v=23.1.0:2:30158)
    at t (desktop_all.min.js?v=23.1.0:2:30460)
l.create @ desktop_all.min.js?v=23.1.0:14
s @ desktop_all.min.js?v=23.1.0:53
(anonymous) @ desktop_all.min.js?v=23.1.0:53
e @ desktop_all.min.js?v=23.1.0:2
t @ desktop_all.min.js?v=23.1.0:2
setTimeout (async)
(anonymous) @ desktop_all.min.js?v=23.1.0:2
c @ desktop_all.min.js?v=23.1.0:2
fireWith @ desktop_all.min.js?v=23.1.0:2
fire @ desktop_all.min.js?v=23.1.0:2
c @ desktop_all.min.js?v=23.1.0:2
fireWith @ desktop_all.min.js?v=23.1.0:2
ready @ desktop_all.min.js?v=23.1.0:2
$ @ desktop_all.min.js?v=23.1.0:2

EDIT 1

It seems like a bug in Apex 23.1.3 (desktop_all.min.js?v=23.1.3)

Steps to re-produce

1. Create a new page
2. Create a region
3. Change its Type to Dynamic Content
4. Write return ''; in PL/SQL Function Body returning a CLOB
5. Change Template to None under Appearance
6. Run the page

Console will log both errors.