fix: do load extension interfaces if early parsing errors out

Apparently we have not been loading them upon error in early parsing.
Debian has python 3.12 patched with some patches from what came after 3.14 (!)
and that broke that interface.  We silently just did not even try to
get those parsers in place.  With this change we would

datalad/cli/parser.py

@@ -128,9 +128,10 @@ def setup_parser(
 
     # when completing and we have no incomplete option or parameter
     # we still need to offer all commands for completion
-    if (completing and status == 'allknown') or (
+    if ((completing and status == 'allknown') or (
             status == 'subcommand' and parseinfo not in
-            get_commands_from_groups(interface_groups)):
+            get_commands_from_groups(interface_groups))
+            or status == 'error'):
         # we know the command is not in the core package
         # still a chance it could be in an extension
         command_provider = 'extension'