In case a background service such as the fingerprint authentication
fails to start we'd just mark the whole authentication process as
failed.
Currently this may happen by just putting a wrong password when an user
has some fingerprints enrolled, the fingerprint gdm authentication
worker may take some time to restart leading to a failure and this is
currently also making the password authentication to fail:
JS ERROR: Failed to start gdm-fingerprint for u: Gio.DBusError:
GDBus.Error:org.freedesktop.DBus.Error.Spawn.Failed:
Could not create authentication helper process
_promisify/proto[asyncFunc]/</<@resource:///org/gnome/gjs/modules/core/overrides/Gio.js:435:45
### Promise created here: ###
_startService@resource:///org/gnome/shell/gdm/util.js:470:42
_beginVerification@resource:///org/gnome/shell/gdm/util.js:495:18
_getUserVerifier@resource:///org/gnome/shell/gdm/util.js:405:14
async*_openReauthenticationChannel@resource:///org/gnome/shell/gdm/util.js:378:22
async*begin@resource:///org/gnome/shell/gdm/util.js:194:18
_retry@resource:///org/gnome/shell/gdm/util.js:561:14
_verificationFailed/signalId<@resource:///org/gnome/shell/gdm/util.js:584:30
_emit@resource:///org/gnome/gjs/modules/core/_signals.js:133:47
finishMessageQueue@resource:///org/gnome/shell/gdm/util.js:268:14
_queueMessageTimeout@resource:///org/gnome/shell/gdm/util.js:273:18
_queueMessageTimeout/this._messageQueueTimeoutId<@resource:///org/gnome/shell/gdm/util.js:288:65
Given that background services are ignored even for queries or any kind
of message, we should not fail the authentication request unless the
default service fails.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1622>