[gimp] app-tools, app: gimp-debug-tool crashing with NULL release_date.

[Jehan <jehanp src gnome org>]

commit d76c8e8cc36cf77c83f0cc97853b89ed910117a4
Author: Jehan <jehan girinstud io>
Date:   Fri Mar 27 19:44:41 2020 +0100

    app-tools, app: gimp-debug-tool crashing with NULL release_date.
    
    The crash dialog was failing to be created when using the last version
    of GIMP!

 app-tools/gimp-debug-tool.c      |  2 +-
 app/widgets/gimpcriticaldialog.c | 14 +++++++++-----
 2 files changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/app-tools/gimp-debug-tool.c b/app-tools/gimp-debug-tool.c
index fbce802e5a..da6f862f99 100644
--- a/app-tools/gimp-debug-tool.c
+++ b/app-tools/gimp-debug-tool.c
@@ -85,7 +85,7 @@ main (int    argc,
   gtk_init (&argc, &argv);
 
   dialog = gimp_critical_dialog_new (_("GIMP Crash Debug"), last_version,
-                                     g_ascii_strtoll (release_date, NULL, 10));
+                                     release_date ? g_ascii_strtoll (release_date, NULL, 10) : -1);
   gimp_critical_dialog_add (dialog, error, trace, TRUE, program,
                             g_ascii_strtoull (pid, NULL, 10));
   g_free (error);
diff --git a/app/widgets/gimpcriticaldialog.c b/app/widgets/gimpcriticaldialog.c
index 3624a2c964..a8e077949c 100644
--- a/app/widgets/gimpcriticaldialog.c
+++ b/app/widgets/gimpcriticaldialog.c
@@ -501,14 +501,18 @@ gimp_critical_dialog_new (const gchar *title,
                           gint64       release_timestamp)
 {
   GtkWidget *dialog;
-  GDateTime *datetime;
-  gchar     *date;
+  gchar     *date = NULL;
 
   g_return_val_if_fail (title != NULL, NULL);
 
-  datetime = g_date_time_new_from_unix_local (release_timestamp);
-  date = g_date_time_format (datetime, "%x");
-  g_date_time_unref (datetime);
+  if (release_timestamp > 0)
+    {
+      GDateTime *datetime;
+
+      datetime = g_date_time_new_from_unix_local (release_timestamp);
+      date = g_date_time_format (datetime, "%x");
+      g_date_time_unref (datetime);
+    }
 
   dialog = g_object_new (GIMP_TYPE_CRITICAL_DIALOG,
                          "title",        title,