Crash report on version 0.88 (window_control.get_icon_pb(win) = None)

[gabdub]

After updating to version 0.88 I started receiving the following crash report:

PythonArgs: ['/usr/lib/mate-applets/mate-dock-applet/dock_applet.py']
Traceback:
 Traceback (most recent call last):
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 2711, in view_opened
     self.window_added(the_app, object)
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 2759, in window_added
     dock_app = self.match_bamf_app_to_dock_app(application)
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 2653, in match_bamf_app_to_dock_app
     self.set_app_icon(dock_app, size)
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 3180, in set_app_icon
     pixbuf = pixbuf.scale_simple(icon_size * scale_factor, icon_size * scale_factor,
 AttributeError: 'NoneType' object has no attribute 'scale_simple'

I'm currently running Ubuntu Mate 19.04.
Seems like pixbuf = window_control.get_icon_pb(win) on dock.py @ 3178 is returning None.

[gabdub]

I forgot to mention that I've only seen the crash at boot time.

[gabdub]

Added if pixbuf is not None: @ line 3179 and the crash moved to:

PythonArgs: ['/usr/lib/mate-applets/mate-dock-applet/dock_applet.py']
Traceback:
 Traceback (most recent call last):
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 2711, in view_opened
     self.window_added(the_app, object)
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 2753, in window_added
     if application.get_desktop_file() is not None:
 AttributeError: 'NoneType' object has no attribute 'get_desktop_file'

[thefossilrecord]

Had the same crash (v0.88 GTK3 Ubuntu Mate 18.04.02) with pixbuf = window_control.get_icon_pb(win) but this was mid-session a while after boot time. I think the follow on crash after your patch is because application is not valid - looking at the code we're already in the state where dock_app is none so maybe it's not safe to assume the application is valid at that point too.

[gabdub]

Yes, checking /var/crash I also have the crash long after boot time.
In every boot some hidden process triggers this issue in my system.

[thefossilrecord]

Documentation for Bamf.Matcher function get_application_for_window says it can return none. One possible fix for the secondary crash would be to add checks in to see whether the result obtained from the call to get_application_for_window returned none. This would stop the call into window_added with an empty application object. The code does do this for the call in window_removed but not for the other places it calls it.

[gabdub]

I applied vkareh's patch #173 by hand and rebooted a couple of times and the crash at boot-time appears to be gone.

[gabdub]

After another reboot, the second crash I reported appears again:

PythonArgs: ['/usr/lib/mate-applets/mate-dock-applet/dock_applet.py']
Traceback:
 Traceback (most recent call last):
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 2711, in view_opened
     self.window_added(the_app, object)
   File "/usr/lib/mate-applets/mate-dock-applet/dock.py", line 2753, in window_added
     if application.get_desktop_file() is not None:
 AttributeError: 'NoneType' object has no attribute 'get_desktop_file'

[thefossilrecord]

In dock.py, you can search for:

the_app = matcher.get_application_for_window(object)
self.window_added(the_app, object)

and

the_app = matcher.get_application_for_window(object)
self.window_removed(the_app, object)

and change them to:

the_app = matcher.get_application_for_window(object)
if the_app is not None:
    self.window_added(the_app, object)

the_app = matcher.get_application_for_window(object)
if the_app is not None:
    self.window_removed(the_app, object)

and see if that improves things.

[gabdub]

I added the two "ifs" and it's working well for now, I will continue testing it.

[gabdub]

0 crash reports in a week!
I'll close the issue when patch #173 is applied and the two ifs are added.