[FW][FIX] point_of_sale: show the loading PoS data error

[fw-bot]

Before this commit, if there was an error, the PoS stays on
the loading page which was confusing for the user.

owp-3834647

---

I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

Forward-Port-Of: #160113
Forward-Port-Of: #159710

[robodoo]

.

[fw-bot]

@pedrambiria @adgu-odoo cherrypicking of pull request #159710 failed.

stdout:

Auto-merging addons/point_of_sale/static/src/app/main.js
CONFLICT (content): Merge conflict in addons/point_of_sale/static/src/app/main.js

stderr:

10:24:19.145007 git.c:463               trace: built-in: git cherry-pick 74901d1fc916fe405e29edc56542efa34f760b8e
error: could not apply 74901d1fc916... [FIX] point_of_sale: show the loading PoS data error
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
----------
status:

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

⚠️ after resolving this conflict, you will need to merge it via @robodoo.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[pedrambiria]

Hello @xmo-odoo
could you please put a security override on this branch?

[xmo-odoo]

@robodoo override=ci/security

[pedrambiria]

robodoo r+