Fix a specific problem when visiting some specific pages like this one:
/auth/config/edit/?provider=PhabricatorPhabricatorAuthProvider:
Stack trace:
[Fri May 19 14:23:35.506028 2023] [php7:notice] [pid 20439] [client 127.0.0.1:39692] [2023-05-19 14:23:35] EXCEPTION: (InvalidArgumentException) Call to phutil_nonempty_string() expected null or a string, got: PhutilSafeHTML. at [<arcanist>/src/utils/utils.php:2127]
[Fri May 19 14:23:35.506647 2023] [php7:notice] [pid 20439] [client 127.0.0.1:39692] arcanist(head=arcpatch-D25049, ref.master=c14785c3795c, ref.arcpatch-D25049=1b6412c24640), phorge(head=arcpatch-D25216_1, ref.master=2df7ea13a387, ref.arcpatch-D25216_1=02b40a9e25eb)
[Fri May 19 14:23:35.506661 2023] [php7:notice] [pid 20439] [client 127.0.0.1:39692] #0 <#2> phutil_nonempty_string(PhutilSafeHTML) called at [<phorge>/src/view/form/control/AphrontFormControl.php:206]
[Fri May 19 14:23:35.506665 2023] [php7:notice] [pid 20439] [client 127.0.0.1:39692] #1 <#2> phutil_tag(string, array, array) called at [<phorge>/src/view/form/PHUIFormLayoutView.php:54]
[Fri May 19 14:23:35.506667 2023] [php7:notice] [pid 20439] [client 127.0.0.1:39692] #2 <#2> PHUIFormLayoutView::render() called at [<phorge>/src/view/form/AphrontFormView.php:160]
Weep 100% backward compatibility, reproducing the implicit cast happening automatically before PHP 8.1
It has also been simplified the non-empty check since that is possible after casting to string.
Closes T15404