[gnome-software/wip/kalev/app-row-unreveal-crash] app row: Avoid emitting "unrevealed" signal when in destruction

[Kalev Lember <klember src gnome org>]

commit f7c62ccf12977357ed0ff09c9eaf5873f0ee5035
Author: Kalev Lember <klember redhat com>
Date:   Tue Oct 13 16:46:11 2020 +0200

    app row: Avoid emitting "unrevealed" signal when in destruction
    
    This avoids a crash when the unreveal animation races with GsUpdatesPage
    reload. See https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1016#note_932622
    for analysis of the exact sequence of events to trigger this.
    
    Fixes: https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1016

 src/gs-app-row.c | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/src/gs-app-row.c b/src/gs-app-row.c
index 721d729b..36acd206 100644
--- a/src/gs-app-row.c
+++ b/src/gs-app-row.c
@@ -465,6 +465,11 @@ static void
 child_unrevealed (GObject *revealer, GParamSpec *pspec, gpointer user_data)
 {
        GsAppRow *app_row = user_data;
+       GsAppRowPrivate *priv = gs_app_row_get_instance_private (app_row);
+
+       /* return immediately if we are in destruction */
+       if (priv->app == NULL)
+               return;
 
        g_signal_emit (app_row, signals[SIGNAL_UNREVEALED], 0);
 }