Using the 17.10 version valgrind shows that error (the system has an invalid snap store login account configured so it might be due to that)
==4467== Invalid read of size 8
==4467== at 0x52E7747: g_type_check_instance_is_a (gtype.c:4008)
==4467== by 0x175E3C: GS_IS_PLUGIN_EVENT (gs-plugin-event.h:34)
==4467== by 0x175E3C: gs_plugin_event_add_flag (gs-plugin-event.c:210)
==4467== by 0x52C1F9C: g_closure_invoke (gclosure.c:804)
==4467== by 0x52D4CDD: signal_emit_unlocked_R (gsignal.c:3635)
==4467== by 0x52DD4B4: g_signal_emit_valist (gsignal.c:3391)
==4467== by 0x52DDECE: g_signal_emit (gsignal.c:3447)
==4467== by 0x52C6463: g_object_dispatch_properties_changed (gobject.c:1080)
==4467== by 0x52C8838: g_object_notify_by_spec_internal (gobject.c:1173)
==4467== by 0x52C8838: g_object_notify (gobject.c:1221)
==4467== by 0x17AECF: gs_plugin_loader_notify_idle_cb (gs-plugin-loader.c:297)
==4467== by 0x5550E24: g_main_dispatch (gmain.c:3148)
==4467== by 0x5550E24: g_main_context_dispatch (gmain.c:3813)
==4467== by 0x55511EF: g_main_context_iterate.isra.30 (gmain.c:3886)
==4467== by 0x555127B: g_main_context_iteration (gmain.c:3947)
==4467== Address 0x2bf16960 is 0 bytes inside a block of size 72 free'd
==4467== at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==4467== by 0x52E6AB0: g_type_free_instance (gtype.c:1943)
==4467== by 0x1783F1: glib_autoptr_cleanup_GObject (gobject-autocleanups.h:25)
==4467== by 0x1783F1: glib_autoptr_cleanup_GsPluginEvent (gs-plugin-event.h:34)
==4467== by 0x1783F1: gs_plugin_loader_create_event_from_error (gs-plugin-loader.c:332)
==4467== by 0x1783F1: gs_plugin_error_handle_failure (gs-plugin-loader.c:410)
==4467== by 0x17953F: gs_plugin_loader_call_vfunc (gs-plugin-loader.c:742)
==4467== by 0x17A073: gs_plugin_loader_run_refine_internal (gs-plugin-loader.c:816)
==4467== by 0x17A58E: gs_plugin_loader_run_refine (gs-plugin-loader.c:950)
==4467== by 0x17B14F: gs_plugin_loader_process_thread_cb (gs-plugin-loader.c:3170)
==4467== by 0x58A5D55: g_task_thread_pool_thread (gtask.c:1328)
==4467== by 0x557900F: g_thread_pool_thread_proxy (gthreadpool.c:307)
==4467== by 0x5578644: g_thread_proxy (gthread.c:784)
==4467== by 0x82D07FB: start_thread (pthread_create.c:465)
==4467== by 0x85FCB0E: clone (clone.S:95)
==4467== Block was alloc'd at
==4467== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==4467== by 0x5556578: g_malloc (gmem.c:94)
==4467== by 0x556E0F5: g_slice_alloc (gslice.c:1025)
==4467== by 0x556E588: g_slice_alloc0 (gslice.c:1051)
==4467== by 0x52E66D4: g_type_create_instance (gtype.c:1848)
==4467== by 0x52C75E7: g_object_new_internal (gobject.c:1797)
==4467== by 0x52C8D84: g_object_new_with_properties (gobject.c:1965)
==4467== by 0x52C9800: g_object_new (gobject.c:1637)
==4467== by 0x175F91: gs_plugin_event_new (gs-plugin-event.c:319)
==4467== by 0x178294: gs_plugin_loader_create_event_from_error (gs-plugin-loader.c:347)
==4467== by 0x178294: gs_plugin_error_handle_failure (gs-plugin-loader.c:410)
==4467== by 0x17953F: gs_plugin_loader_call_vfunc (gs-plugin-loader.c:742)
==4467== by 0x17A073: gs_plugin_loader_run_refine_internal (gs-plugin-loader.c:816)
Reported upstream as well on https:/